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

---

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

Calcium and phosphorus metabolism is mainly regulated by PTH through its actions on kidney and bone. PTHrP, which is associated with the hypercalcemia of malignancy syndrome, binds to and activates the same receptor that PTH does. cDNA clones of PTH/PTHrP receptors from rat osteosarcoma (ROS 17/2.8) and opossum kidney (OK) cells are highly homologous and are members of a novel G protein-linked receptor family that includes calcitonin, glucagon, GLP-1, GHRH, VIP, and secretin receptors. Analysis of the protein sequence predicts a receptor with 7 transmembrane domains, a 155 amino acids (aa) extracellular (EC) N-terminal, and 130aa intracellular C-terminal domaina. The extracellular domain has 6 conserved cysteines and 4 potential glycosylation sites. When transfected in COS cells, both receptors are able to bind PTH and PTHrP active fragments with equal affinity. Likewise, agonists activate both adenylate cyclase and phospholipase C efficiently. The N-terminal EC domain and the first EC loop seem to determine the receptor binding capacity with the agonists. Activation of adenylate cyclase and phospholipase C might involve multiple sites between the 3rd helix and the C-terminal tail. Partial characterization of the rat PTH/PTHrP receptor gene demonstrates the existence of at least 15 exons. The first six transmembrane domains are encoded by separated exons. The PTH/PTHrP receptor mRNA is expressed mainly in kidney and bone, and also is widely expressed in many tissues, but not all. A major 2.3-2.5 kb transcript is observed in all these tissues. Nevertheless, 2 larger transcripts are observed in kidney and liver, and multiple smaller mRNA species are observed in kidney, skin, and testis.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:[Mode of action of parathyroid hormone (PTH) and PTH-related peptide (PTHrP) in target organs]. 785 77

We tested whether the protein kinase C (PKC) modulation of PTH-sensitive adenylate cyclase in ROS 17/2.8 cells is affected by the glucocorticoid dexamethasone and the vitamin D hormone 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. Basal and PTH- and forskolin-stimulated adenylate cyclase activities were determined in the presence or absence of 100 nM phorbol 12-myristate 13-acetate (PMA), the activator of PKC, in ROS 17/2.8 cells that had been previously cultured with or without dexamethasone or 1,25(OH)2D3. Dexamethasone treatment increased the basal, PMA-, PTH-, (PTH + PMA)- and (forskolin + PMA)-sensitive adenylate cyclase while 1,25(OH)2D3 decreased these effects. The stimulatory and inhibitory effects were dose-dependent with respect to dexamethasone and 1,25(OH)2D3, respectively. Dexamethasone increased, while 1,25(OH)2D3 decreased the maximal activity of both PTH-sensitive and PKC-modulated PTH-sensitive adenylate cyclase without affecting the half-maximal concentration (ED50) of PTH required for the activation of the enzyme. Additionally, dexamethasone, 1,25(OH)2D3 and PKC did not affect each other's ED50. Our results suggest that the effects of dexamethasone, 1,25(OH)2D3 and PKC on PTH-sensitive adenylate cyclase in ROS 17/2.8 cells are independent of each other.
...
PMID:Modulation of parathyroid hormone-sensitive adenylate cyclase in ROS 17/2.8 cells by dexamethasone 1,25-dihydroxyvitamin D3 and protein kinase C. 827 78

Exposure of ROS 17/2.8 cells to dexamethasone (DEX) or retinoic acid (RA) increases and decreases, respectively, adenylate cyclase activity (ACA) in response to isoproterenol, forskolin, guanylylimidodiphosphate, or NaFl. Despite dramatic changes in ACA, there were no significant changes in levels of cholera toxin- or pertussis toxin (PT)-dependent ADP-ribosylation of membranes prepared from cells after DEX or RA exposure as compared to controls. Similarly, immunochemical detection of alpha S, alpha i1-3, and alpha O, as well as Northern blot analysis of messenger RNA for each of the respective GTP binding proteins, also failed to demonstrate an influence of DEX or RA when contrasted with controls. In a novel use of the cyc- reconstitution assay, wherein the influence of inhibitory guanine nucleotide binding proteins in the extracts of control, DEX-, and RA-treated membranes is removed by a previous 24-h incubation with PT in the intact cell, we demonstrate that this PT treatment markedly enhances ACA in the cyc- reconstitution assay for all three preparations, but that the fold-increase due to PT-treatment is greatest in RA-treated cells. The greater magnitude of the effect of PT on RA-treated ROS 17/2.8 cells, in the absence of any obvious quantitative changes in the levels of the PT substrates, suggests that the effect of RA on ROS 17/2.8 cells appears to be an augmentation of the influence of inhibitory guanine nucleotide binding proteins, ultimately leading to reduced ACA.
...
PMID:Opposing influences of dexamethasone and retinoic acid on adenylate cyclase activity in ROS 17/2.8 cells. 841 27

Chicken polyclonal antibodies were prepared against a synthetic peptide corresponding to the first 36 N-terminal amino acids of parathyroid hormone-related protein (PTHrP) by immunizing laying hens. Significant increases of antibodies to PTHrP were first detected after the second immunization. Production of anti-PTHrP egg yolk antibodies peaked 1-2 weeks after the second through sixth immunizations and declined over a period of 2-4 weeks. Polyclonal IgG (IgY) to PTHrP was purified from the egg yolks with high levels of PTHrP specific binding. The anti-PTHrP IgG was used to develop a radioimmunoassay for PTHrP that was able to detect 100 pg PTHrP ml-1 (23 pM) in conditioned cell culture medium. The anti-PTHrP IgG was bound to a solid phase and utilized to immunopurify iodinated [Tyr36]-PTHrP (1-36). Anti-PTHrP IgG inhibited the in vitro biologic activity of PTHrP as demonstrated by the inhibition of adenylate cyclase stimulation in a rat osteoblast-like cell line (ROS 17/2.8). The anti PTHrP IgG was immunopurified and utilized for immunohistochemical localization of PTHrP in canine skin. Chickens were advantageous in producing large amounts of high affinity, neutralizing antibodies to a highly conserved mammalian protein such as PTHrP. The antibodies will be useful to investigate the function and metabolism of PTHrP in vivo and in vitro.
...
PMID:Studies on chicken polyclonal anti-peptide antibodies specific for parathyroid hormone-related protein (1-36). 843 Apr 99

Parathyroid hormone (PTH) activates both adenylate cyclase and phospholipase C in target cells, and cloned PTH/PTH-related protein (PTHrP) receptor can mediate both responses when expressed in host cells such as LLC-PK1 renal epithelial cells. Because calcitonin (CT) is known to augment 70-kDa heat shock protein (HSP70) mRNA by an adenosine 3',5'-cyclic monophosphate (cAMP)-independent mechanism in LLC-PK1 cells, we examined regulation of HSP70 transcription by PTH in these cells. Like CT, human PTH-(1-34) [hPTH-(1-34); 10(-10) to 10(-7) M)] increased porcine HSP70 mRNA and human HSP70 promoter-chloramphenicol acetyltransferase (CAT) expression within 4 h in LLC-PK1 cells that stably express > or = 100,000 PTH/PTHrP receptors per cell. The effect of PTH on HSP70 mRNA was not mimicked by cAMP analogues, forskolin, phorbol esters, Ca2+ ionophores, or alpha-thrombin; was insensitive to pertussis toxin; and was not due to increased mRNA stability. The upregulation of HSP70 gene transcription by hPTH (and CT) was clearly observed even after deletion of the functional heat shock consensus element in the promoter region of the human HSP70/CAT reporter. Upregulation of HSP70 transcription via endogenous PTH receptors also was observed in the osteoblastic cell lines SaOS-2 and ROS 17/2.8. Regulation of HSP70 gene transcription by PTH may be a common cellular response to the hormone, which, in some cells, may not be mediated by activation of adenylate cyclase or protein kinase C.
...
PMID:Regulation of HSP70 by PTH: a model of gene regulation not mediated by changes in cAMP levels. 876 37

The role of hormonal status in the development of aluminum (Al)-dependent renal osteodystrophy, which is characterized by reduced bone matrix deposition, still remains largely unknown. To address this question, we used the osteoblast-like osteosarcoma cell line ROS 17/2.8 to evaluate the role of Al on parathyroid hormone (PTH)- and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3)-dependent activities in these cells. Al (1 microM) caused an inhibition of basal and 1,25(OH)2D3-induced alkaline phosphatase, but only at low doses (< 1 nM) of the steroid. Al partly inhibited basal osteocalcin (OC) secretion in ROS cells (p < 0.001), and the dose-dependent increase in 1,25(OH)2D3-induced OC release by these cells was also reduced by 1 microM Al at low concentrations of the steroid (< or = 1 nM), whereas high doses of 1,25(OH)2D3 (> or = 5 nM) totally prevented the inhibiting effects of Al. Al also had strong inhibitory actions on PTH-dependent cAMP production by ROS cells over the concentration range tested (0.5-50 nM). This inhibitory action of Al was also observed for PTH-related peptide- (PTHrp, 50 nM) but not for Isoproterenol-dependent (100 nM) cAMP formation. To evaluate more fully the mechanism of this inhibition of cAMP formation, we investigated the effect of Al on toxin-modulated, G protein-dependent regulation of cAMP formation and on the activation of adenylate cyclase by Forskolin. Cholera toxin (CT, 10 micrograms/ml), applied to cells for 4 h prior to PTH challenge, enhanced cAMP production about 2-fold above PTH alone (p < 0.001), a process that was further stimulated by Al. Pertussis toxin (PT, 1 microgram/ml, 4 h) did not modify basal PTH-dependent cAMP formation by ROS cells. However, PT treatment prevented the inhibitory effect of Al on cAMP formation by these cells (p < 0.025). The stimulation of adenylate cyclase by Forskolin (0.1 and 1 microM), which bypasses G protein regulation, was not modified by Al, indicating that Al does not affect adenylate cyclase directly. Northern blot analysis of PTH receptor mRNA levels showed that Al did not modify PTH receptor message in ROS cells. Likewise, Western blot analyses of G protein subunits showed that Al did not significantly alter Gs alpha subunit levels, in accordance with the results obtained for cAMP-dependent formation in response to CT. In contrast, Gi alpha-1 and Gi alpha-2 subunits were decreased by Al treatment, consistent with PT-restricted increases in cAMP formation in Al-treated ROS cells. Taken together, these results suggest that Al has multiple actions in osteoblast-like ROS cells. The effects of Al are modulated by hormonal control of the pathways investigated. Al affects 1,25(OH)2D3-regulated functions only when this steroid is low. Al has large inhibitory effects on PTH- and PTHrp-dependent cAMP formation. This last feature is related to the ability of Al to alter the G protein transducing pathway for PTH/PTHrp-dependent formation of cAMP since it does not affect adenylate cyclase activity directly and does not affect the PTH receptor message level. Thus, Al has stronger deleterious effects in osteoblast-like cells with an already compromised 1,25(OH)2D3 status and can modulate specifically PTH/PTHrp-mediated cAMP formation at the postreceptor level.
...
PMID:Influence of aluminum on the regulation of PTH- and 1,25(OH)2D3-dependent pathways in the rat osteosarcoma cell line ROS 17/2.8. 962 27

A series of conformationally-restricted analogues of hPTH was prepared, based on the parent peptide agonist, cyclo(Lys(18)-Asp(22))[Ala(1),Nle(8),Lys(18),Asp(22),Leu(27)]hPTH(1-31)NH(2) (2, EC(50)=0.29nM). Truncation of 2 at either the N- or C-termini resulted in peptides with reduced agonist activity as measured by stimulation of adenylate cyclase activity in the rat osteosarcoma cell line (ROS 17/2.8). Alanine- and glycine-scanning at the N-terminus of 2 was consistent with data previously obtained on linear hPTH(1-34). Other locations within the primary sequence of hPTH(1-31)NH(2) were evaluated by the placement of the [i, i+4] lactam constraining element. Ring size and lactam orientations at the 18-22 positions were also examined.
...
PMID:Analogues of human parathyroid hormone (1-31)NH(2): further evaluation of the effect of conformational constraint on biological activity. 1181 62

cAMP/PKA signaling transiently stimulates mRNA expression of immediate-early genes, including IL-6 and c-fos. We confirmed that these mRNAs are transiently stimulated by parathyroid hormone (PTH) in ROS 17/2.8 osteoblastic cells. Consistent with the role for cAMP/PKA signaling in this response, PTH induces transient cAMP elevation, PKA activation, and cAMP-responsive element-binding protein (CREB) phosphorylation. Our goal was to determine whether termination of immediate-early gene expression is due to receptor desensitization or cAMP degradation. The approaches used were 1) inhibition of PTH receptor desensitization with G protein-coupled receptor kinase 2 (GRK2) antisense oligonucleotides or antisense plasmids, 2) sustained activation of adenyl cyclase with forskolin, and 3) inhibition of cAMP degradation with 3-isobutyl-1-methylxanthine. These experiments show that mechanisms downstream of receptor desensitization and cAMP degradation are primarily responsible for termination of PKA activity, CREB phosphorylation, and immediate-early gene expression. Similar conclusions were also obtained in response to PTH in a second osteoblastic cell line (MC3T3-E1) and in response to isoproterenol in NIH3T3 fibroblasts. This conclusion may therefore reflect a general mechanism for termination of immediate-early gene expression after induction by cAMP/PKA.
...
PMID:Termination of immediate-early gene expression after stimulation by parathyroid hormone or isoproterenol. 1237 4

Dihydropyrimidinase-like 3 (DPYSL3) is believed to play a role in neuronal differentiation, axonal outgrowth and neuronal regeneration, as well as cytoskeleton organization. Recently we have shown that glutamate excitotoxicity and oxidative stress result in calpain-dependent cleavage of DPYSL3, and that NOS plays a role in this process [R. Kowara, Q. Chen, M. Milliken, B. Chakravarthy, Calpain-mediated truncation of dihydropyrimidinase-like 3 protein (DPYSL3) in response to NMDA and H2O2 toxicity, J. Neurochem. 95 (2005) 466-474; R. Kowara, K.L. Moraleja, B. Chakravarthy, Involvement of nitric oxide synthase and ROS-mediated activation of L-type voltage-gated Ca(2+) channels in NMDA-induced DPYSL3 degradation, Brain Res. 1119 (2006) 40-49]. The present study investigates the involvement of PLA(2) signaling in NMDA-induced DPYSL3 degradation. Exposure of rat primary cortical neurons (PCN) to PLA(2) and COX-2 inhibitors significantly prevented NMDA-induced DPYSL3 degradation. Since the metabolic product of PLA(2) signaling, PGE(2), which augments toxic effect of NMDA, is known to stimulate cAMP, the effect of adenyl cyclase activator (forskolin plus IBMX) and inhibitor (MDL12,300) on NMDA-induced DPYSL3 degradation was tested. Our data indicate that the activation of adenyl cyclase contributes to NMDA-induced DPYSL3 degradation. Furthermore, cAMP-dependent protein kinase (PKA) inhibitor PKI (14-22) provided additional evidence of PKA involvement in NMDA-induced DPYSL3 degradation. In summary, the obtained data show the contribution of PLA(2) signaling to NMDA-induced calpain activation and subsequent degradation of synaptic protein DPYSL3.
...
PMID:PLA(2) signaling is involved in calpain-mediated degradation of synaptic dihydropyrimidinase-like 3 protein in response to NMDA excitotoxicity. 1805 48

To examine the possibility of luteolin as a whitening agent, we measured antioxidant activity using DPPH assay, NBT/XO assay and intracellular ROS scavengning assay and depigmenting activity using tyrosinase assay, alpha-MSH-induced melanin production in B-16 cells. Luteolin showed dose-dependent anti-oxidant activity in DPPH, NBT/XO and intracellular ROS assay. Also, luteolin directly inhibited xanthine oxidase activity in a dose-dependent manner. Although luteolin did not directly inhibit tyrosinase activity, it dose-dependently inhibited both tyrosinase activity and melanin production in B16 melanoma cells stimulated by 1 microM alpha-MSH. Luteolin dose-dependently inhibited cAMP levels in B16 melanoma cells stimulated by 1 microM alpha-MSH and 1 microM forskolin, which suggest that luteolin directly inhibits adenyl cyclase in B16 melanoma cells. Therefore, these results suggest that whitening activity of luteolin may be due to the inhibition of adenyl cyclase involved in the signal pathway of alpha-MSH in B16 melanoma cells.
...
PMID:Whitening activity of luteolin related to the inhibition of cAMP pathway in alpha-MSH-stimulated B16 melanoma cells. 1880 60


<< Previous 1 2 3 4 5 6 Next >>

---