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:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calcitonin gene-related peptide (CGRP) has previously been shown to coexist with acetylcholine in spinal cord motoneurons and to stimulate adenylate cyclase in skeletal muscle cells. We now demonstrate that in cultured chick myotubes whose phosphoinositides have been labeled with [3H]inositol, CGRP enhanced the accumulation of [3H]inositol mono-, bis-, and trisphosphates. Rat CGRP-I (rCGRP) (0.1 microM) elicited a transient increase in [3H]inositol 1,4,5-trisphosphate, as well as a more sustained elevation of [3H]inositol 1,3,4-trisphosphate levels. In the presence of Li+, rCGRP evoked an approximately 3-fold increase of [3H]inositol monophosphate levels, which persisted for up to 1 h. This effect of rCGRP was concentration-dependent, the half-maximal response being obtained at 1 nM. Since rCGRP also accelerated the rate of synthesis of [3H]inositol-containing lipids, it appears that the peptide acts by stimulating phosphoinositide turnover in chick myotubes. Agents that either mimic or elevate intracellular cyclic AMP also enhanced the synthesis of [3H]inositol-containing lipids, and the accumulation of inositol phosphates, suggesting that the effects of rCGRP are mediated, at least in part, via the activation of adenylate cyclase. This hypothesis was strengthened by the non-additivity of the inositol phosphate responses elicited by rCGRP and other cAMP-mobilizing agents, and by the sensitivity of these responses to various pharmacological treatments. The present results provide an example of positive interaction between cAMP and the phosphoinositide signaling system. They further suggest that a coexisting neuropeptide may exert pleiotropic actions upon its target cell by stimulating multiple signal transduction pathways.
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PMID:Calcitonin gene-related peptide and cyclic AMP stimulate phosphoinositide turnover in skeletal muscle cells. Interaction between two second messenger systems. 253 20

From this study, we predicted that the human calcitonin gene-related peptide (hCGRP) fragment hCGRP-(8-37) would be a selective antagonist for CGRP receptors but an agonist for calcitonin (CT) receptors. In rat liver plasma membrane, where CGRP receptors predominate and CT appears to act through these receptors, hCGRP-(8-37) dose dependently displaced 125I-[Tyr0]rat CGRP binding. However, hCGRP-(8-37) had no effect on adenylate cyclase activity in liver plasma membrane. Furthermore, hCGRP-(8-37) inhibited adenylate cyclase activation induced not only by hCGRP but also by hCT. On the other hand, in LLC-PK1 cells, where calcitonin receptors are abundant and CGRP appears to act via these receptors, the bindings of 125I-[Tyr0]rat CGRP and 125I-hCT were both inhibited by hCGRP-(8-37). In contrast to liver membranes, interaction of hCGRP-(8-37) with these receptors led to stimulation of adenosine 3',5'-cyclic monophosphate (cAMP) production in LLC-PK1 cells, and moreover, this fragment did not inhibit the increased production of cAMP induced not only by hCT but also by hCGRP. Thus hCGRP-(8-37) appears to be a useful tool for determining whether the action of CGRP as well as that of CT is mediated via specific CGRP receptors or CT receptors.
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PMID:Calcitonin gene-related peptide receptor antagonist human CGRP-(8-37). 253 79

Atrial natriuretic factor (ANF) has been suggested to exert a tubular effect on the mammalian nephron, perhaps in part by interacting with other hormones. In the present study, the effect of ANF was examined on glomeruli (Gm) and different renal tubule segments including medullary (MAL) and cortical thick ascending limb (CAL) and cortical (CCT), outer medullary (OMCT) and inner medullary collecting tubules (IMCT). This effect of ANF was assessed by alteration in adenylate cyclase and cGMP in the various nephron segments in the presence and absence of arginine vasopressin (AVP), parathyroid hormone (PTH) and calcitonin (SCT). An effect of ANF (10(-8) M) was not demonstrated on adenylate cyclase (fmol cAMP formed/30 min/micrograms protein) in Gm, CAL, MAL, CCT, OMCT or IMCT. Nor did ANF (10(-8) M) interfere with the effect of PTH (5 IU/ml) on the Gm (PTH 35.1 +/- 3.7 vs. PTH + ANF 32.5 +/- 1.8, NS), CAL (PTH 50.5 +/- 10.9 vs. PTH + ANF 46.2 +/- 1.4, NS) or AVP (10(-8) M) on the CCT (AVP 40.8 +/- 6.6 vs. AVP + ANF 33.0 +/- 3.1, NS), OMCT (AVP 56.0 +/- 11.8 vs. AVP + ANF 42.1 +/- 6.7, NS), IMCT (AVP 66.5 +/- 4.6 vs. AVP + ANF 53.5 +/- 7.0, NS) or MAL (AVP 15.5 +/- 1.6 vs. AVP + ANF 14.0 +/- 2.6, NS). ANF also did not affect SCT (1.5 x 10(-8) M)-induced adenylate cyclase on CCT (SCT 69.8 +/- 11.3 vs. SCT + ANF 79.9 +/- 7.2, NS). ANF (10(-8) M), however, significantly increased cGMP in the Gm (6.4 +/- 1.7 to 121.3 +/- 32.4 fmol/micrograms protein, P less than 0.001) and IMCT (0.63 +/- 0.16 to 1.46 +/- 0.29 fmol/micrograms protein, P less than 0.05). However, no effect of ANF on cGMP was observed in the CAL, CCT, OMCT, and MAL even at 10(-7) M ANF. PTH (5 IU/ml) did not alter either basal or ANF-stimulated cGMP in the Gm. Also, specific ANF binding was studied in the microdissected IMCT. Kd was 6.08 x 10(-9) M and Bmax was 8.07 x 10(-11) M.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enzymatic and binding effects of atrial natriuretic factor in glomeruli and nephrons. 254 Mar 77

In curarized rat skeletal muscle, rat calcitonin gene-related peptide (CGRP), a peptide coexisted with acetylcholine in the motor nerve terminal, increased the isometric twitch force, accompanied by an increase in the active state intensity of shortening, prolonged duration of the active state and additive effect of a phosphodiesterase inhibitor; the results reflect a potentiation in the sarcoplasmic calcium transport system. This CGRP effect was enhanced by cholera toxin, suggesting the activation of guanine nucleotide binding regulatory protein (G protein) that stimulates adenylate cyclase (Gs). The pertussis toxin (IAP), a factor to prevent the cyclic AMP decrease by inactivating the G protein that inhibits adenylate cyclase (Gi), provided no effect on the action of CGRP. The existence of CGRP binding site in the sarcolemmal membrane was confirmed by Scatchard analysis of binding data; affinity of the binding site for CGRP was decreased in the presence of guanosine-5'-[gamma-thio]triphosphate (GTP gamma S). The Gs protein is thus implicated in the CGRP binding site and intracellular processes of signal transduction. CGRP did not modify the neuromuscular transmission and cable properties of the muscle membrane.
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PMID:Effect of calcitonin gene-related peptide on skeletal muscle via specific binding site and G protein. 254 67

Basolateral membranes were prepared from rat renal cortex by density gradient centrifugation. Their purity was confirmed by electron microscopy and by marker enzyme enrichment. The basolateral membrane preparation was shown to be derived predominantly from the proximal renal tubule by measurement of hormone-stimulated adenylate cyclase; marked stimulation of adenylate cyclase was found with parathyroid hormone, but not with isoprenaline, antidiuretic hormone or calcitonin. A single class of specific high-affinity [3H]angiotensin II-binding site was identified in the basolateral membrane preparation which, after correction of results for tracer degradation, showed equilibrium dissociation constant of 0.23 nmol/l and binding site concentration of 485.8 fmol/mg protein. Binding sites for [3H]angiotensin II were measured in basolateral membranes prepared from rats fed diets with a low, normal or high sodium content. A trend of increased binding site density with reduced sodium intake was found which did not reach statistical significance. No effect on affinity was demonstrated. Treatment of rats on a low-sodium diet with captopril (500 mg/l drinking water) caused a significant reduction in binding site density; no effect on affinity was demonstrated. These findings suggest that the density of angiotensin II receptors at this site is altered by the activity of the renin-angiotensin system.
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PMID:[3H]angiotensin II binding to basolateral membranes from rat proximal renal tubule: effect of sodium intake and captopril. 254 61

T47D human breast cancer cells and BEN human lung cancer cells were preincubated with the tumor-promoting phorbol ester phorbol 12-myristate 13-acetate (PMA). In both cell lines there was a decrease in the binding of 125I-labeled salmon calcitonin ([125I]sCT) which was dependent on the dose and time of exposure to PMA. The effect on binding comprised at least two components: the apparent affinity for binding of [125I]sCT was decreased by PMA, and the rate of internalization of bound [125I]sCT was increased more than 2-fold in the presence of PMA. By using dinitrophenol to inhibit cellular metabolic energy and, therefore, receptor internalization, the PMA effects on receptor affinity were dissociated from those on endocytosis. The effects on binding were reflected in a decreased stimulation by sCT of adenylate cyclase activity. This was specific for the calcitonin receptor system, since PMA had no effect on prostaglandin-E2-stimulated adenylate cyclase in the T47D cell. Protein kinase-C (PKC) was implicated in the inhibitory effects of PMA on both binding and adenylate cyclase activation, since inhibition was reduced by simultaneous incubation with the PKC inhibitors H7 and H8. These results suggest that PKC is capable of mediating down-regulation of the CT receptor, and this is most likely by phosphorylation of the receptor itself or an associated protein.
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PMID:Protein kinase-C-induced down-regulation of calcitonin receptors and calcitonin-activated adenylate cyclase in T47D and BEN cells. 255 60

Human calcitonin gene related peptide (hCGRP) has been shown to release prostacyclin from cultured human endothelial cells and activate adenylate cyclase in endothelial cell membrane preparations. Human endothelial cells are difficult to obtain, so a bovine aortic endothelial cell model has been used to investigate the actions of hCGRP further. Bovine aortic endothelial cells were cultured and membranes prepared from them. In these membrane fractions there was a concentration dependent activation of adenylate cyclase by hCGRP, which required the presence of guanosine 5' triphosphate. Basal activity of adenylate cyclase was 41.5 pmol.min-1.mg-1 protein. The concentration for half maximum activation of adenylate cyclase (Kact) by hCGRP was 842 nM. The maximum increase in adenylate cyclase activity above basal in response to hCGRP was 180 pmol cyclic adenosine monophosphate.min-1.mg-1 protein. A [tyr degree] substituted analogue of hCGRP [( tyr degree]-hCGRP) also activated adenylate cyclase (Kact 2.2 microM) but the maximum stimulation by [tyr degree]-hCGRP was less than that obtained with native peptide. The same analogue partially inhibited the hCGRP dependent activation of adenylate cyclase (Ki = 2 microM). These studies show that hCGRP acts on a receptor on endothelial cells to activate adenylate cyclase and that [tyr degree]-hCGPO is a partial agonist at this receptor. The potent vasodilator properties of hCGRP may be mediated through or modified by its interaction with endothelial cells.
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PMID:Calcitonin gene related peptide (CGRP) activates adenylate cyclase of bovine aortic endothelial cells: guanosine 5' triphosphate dependence and partial agonist activity of a tyrosinated analogue. 255 94

The adenylate cyclase activator forskolin (1-10 mumol/L) inhibited 45Ca release from parathyroid hormone (PTH; 10 nmol/L) stimulated prelabeled neonatal mouse calvaria in short term culture (24 h). This effect of forskolin was potentiated by rolipram, Ro 20-1724, and isobutyl-methylxanthine, three structurally different inhibitors of cyclic AMP phosphodiesterase. Forskolin (10 mumol/L) and calcitonin (30 mU/mL) inhibited the mobilization of stable calcium and inorganic phosphate as well as the release of the lysomal enzymes beta-glucuronidase and beta-N-acetylglucosaminidase from PTH-stimulated unlabeled bones. Osteoclasts in PTH-stimulated calvaria showed active ruffled borders with numerous membrane infoldings. Treatment of PTH-stimulated bones with forskolin and calcitonin resulted in a rapid (2 h) loss of the active ruffled border. In addition, forskolin and calcitonin induced similar changes with respect to the number and size distribution of cytoplasmic vesicles in PTH-activated osteoclasts. After 24 h, all signs of osteoclast inactivation were still prominent, whereas after 48 h of treatment with forskolin or calcitonin, the reappearance of a ruffled border on a number of osteoclasts signaled an escape from the inhibitory action of both calcitonin or forskolin. These data indicate that forskolin inhibits bone resorption by a cyclic AMP dependent mechanism and that the effect of forskolin and calcitonin on bone resorption and osteoclast morphology are comparable. These observations lend further support to the view that cyclic AMP may be an intracellular mediator of the inhibitory action of calcitonin on multinucleated osteoclasts.
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PMID:Comparison between the effects of forskolin and calcitonin on bone resorption and osteoclast morphology in vitro. 260 53

Peculiarities in hormonal regulation of adenylate cyclase (AC) were studied in large bowel tumors to establish criteria of their hormonal dependence. The investigation showed a diminished basal activity of AC matched by decreased response to sodium fluoride, glucagon, and vasoactive intestinal peptide (VIP) in tumors as compared with normal intestinal mucosa. Some cases revealed an increased response of AC to a nonspecific ("inappropriate") stimulator--calcitonin. This was rather typical of colonic tumors while a diminished response to specific ("appropriate") stimulation by VIP and glucagon was more frequent in rectal cancer. The results showed a relationship between hormonal regulation of AC activity and lipid composition of tumor tissue, thus suggesting the possibility of influencing the hormone dependence of intestinal tumors by drugs used to eliminate disturbance of fat-carbohydrate metabolism.
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PMID:Peculiarities of hormonal regulation of adenylate cyclase and lipid composition in colonic and rectal tumors. 277 Sep 32

The occurrence, effects and sensitivity to capsaicin and stimulation of adenylate cyclase of calcitonin gene-related peptide (CGRP) in the rat kidney have been investigated. CGRP-like immunoreactivity was higher in the medulla than in the papilla and the cortex. Capsaicin pretreatment significantly reduced CGRP-like immunoreactivity in the medulla and papilla while a small reduction was found in the cortex. CGRP-immunoreactive nerve fibres were observed surrounding blood vessels and occasionally in the vicinity of renal tubules and between the collecting ducts in the papilla. Some CGRP-immunoreactive fibres were also seen in kidneys from capsaicin-pretreated rats. Infusion of capsaicin (1 microM) through the renal artery of isolated and perfused rat kidney increased the CGRP-like immunoreactivity outflow from the venous effluent. This effect exhibited desensitization at the second challenge with the drug. Infusion of either capsaicin (1 microM) or CGRP (1 microM) reduced the increase of perfusion pressure induced by norepinephrine in isolated perfused rat kidney. Plasma protein extravasation was studied in the various regions of the rat kidney following infusion of capsaicin. No significant change was observed in the medulla, papilla or cortex after capsaicin administration. Adenylate cyclase activity was studied in membrane preparations from cortex, medulla and papilla of rat kidney. Cortical and medullary adenylate cyclase was stimulated in a concentration-dependent manner by salmon calcitonin, rat calcitonin and rat CGRP. Salmon calcitonin in these two areas showed half-maximal effective concentration approximately 1000 times lower and maximal stimulation only slightly higher than those of rat calcitonin and rat CGRP. However, in the papilla, only rat CGRP was able to induce a 60% increase of enzyme activity (half-maximal effective concentration, 19 +/- 1.6 nM). It is concluded that CGRP contained in capsaicin-sensitive sensory nerve may exert a local function in discrete areas of the rat kidney.
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PMID:Calcitonin gene-related peptide in the rat kidney: occurrence, sensitivity to capsaicin, and stimulation of adenylate cyclase. 278 87


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