Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In these structure activity studies, the 46 analogs of the 27-amino-acid form of the pituitary-adenylate-cyclase-activating peptide, PACAP(1-27), and the 38-amino-acid form, PACAP(1-38), were either monosubstituted or bisubstituted at positions 1-3, 20 and 21 or N-terminally shortened. All analogs were compared on human neuroblastoma NB-OK-1 cell membranes for their ability to occupy 125I-[AcHis1]PACAP(1-27)-labelled receptors (AcHis, N alpha-acetylhistidine) and to activate adenylate cyclase (in terms of potency and intrinsic activity). The monophasic slope of dose/effect curves on both parameters suggested interaction with one class of PACAP receptor. Residues 28-38 in the C-terminally extended peptide, PACAP(1-38), played a favorable role in recognition, in that receptors coupled to adenylate cyclase were, in general, more sensitive to PACAP(1-38) analogs than to the corresponding PACAP(1-27) analogs. At variance with PACAP(6-27), PACAP(6-38) was well recognized and acted as a potent competitive antagonist (Ki 1.5 nM). Residues 1-3 were all important in enzyme activation: modification of the beta-turn potential gave full agonists (the LAla2 and DAla2 derivatives) or partial agonists (LPhe2 and DPhe2; LArg2 and DArg2; Glu3 and Asn3). Finally, a proper alpha-helix was also important: the combined substitution of Lys21/Lys22 by Gly21/Gly22 decreased the binding affinity sharply.
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PMID:Structural requirements for the occupancy of pituitary adenylate-cyclase-activating-peptide (PACAP) receptors and adenylate cyclase activation in human neuroblastoma NB-OK-1 cell membranes. Discovery of PACAP(6-38) as a potent antagonist. 132 Oct 43

N-terminally shortened analogs of the 27-amino-acid and 38-amino-acid forms of the pituitary-adenylate-cyclase-activating neuropeptide, PACAP(1-27) and PACAP(1-38), were synthesized by a solid-phase method. Systematic deletion of the first 13 amino acids of both PACAP was tested by evaluating their ability to occupy the specific and selective PACAP receptor of human neuroblastoma NB-OK-1 cell membranes and to stimulate adenylate cyclase or, when inactive per se, to inhibit PACAP-stimulated adenylate cyclase activity. For each peptide, the Kact (concentration required for half-maximal adenylate cyclase activation) or Ki [concentration required to shift the dose/response curve of PACAP(1-27) twofold to the right] was in good agreement with the corresponding IC50 [concentration inhibiting 50% of 125I-[AcHis1]PACAP(1-27) binding to membranes], suggesting interaction with the same homogeneous class of adenylate cyclase-coupled receptors. The deletion of the two first amino acids (His1 and Ser2) sufficed to decrease the affinity for receptors and to suppress the capacity to activate adenylate cyclase. The shorter fragments 3-27 and 3-38, 4-27 and 4-38, 5-27 and 5-38, 6-27 and 6-38, 7-27 and 7-38, 8-27 and 8-38, and 9-27 and 9-38 were all competitive antagonists of PACAP(1-27)-stimulated activity with the N-terminally shortened PACAP(1-38) derivatives being 4-30-fold more potent than the equivalent PACAP(1-27) derivatives. In this group PACAP(6-38) was the most potent antagonist (Ki 1.5 nM). Surprisingly, the N-terminally shorter fragments 10-27 and 10-38, 11-27 and 11-38, 12-27 and 12-38, 13-27 and 13-38, and 14-27 and 14-38 were again able to stimulate adenylate cyclase, the smallest fragments, PACAP(14-27) and PACAP(14-38), being the most potent and efficient (Kact 2 microM and 0.1 microM, respectively). In this group of agonists, PACAP(1-38) derivatives deleted at the N-terminus were also more potent than the equivalent PACAP(1-27) derivatives.
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PMID:Antagonistic properties are shifted back to agonistic properties by further N-terminal shortening of pituitary adenylate-cyclase-activating peptides in human neuroblastoma NB-OK-1 cell membranes. 132 69

PACAP (pituitary adenylate-cyclase-activating peptide)-binding receptors were investigated in membranes from the rat pancreatic acinar cell line, AR 4-2J, the rat hippocampus and the human neuroblastoma cell line NB-OK, by 125I-PACAP(1-27) (amino acid residues 1-27 of N-terminal amidated PACAP) binding and adenylate cyclase activation. The relative binding of 125I-PACAP(1-27) to the receptor, and ability to activate adenylate cyclase were PACAP greater than or equal to PACAP(1-27) greater than PACAP(2-38) greater than PACAP(1-9)-VIP(10-28)(PACAP-VIP) greater than PACAP(2-27) greater than [Ser9,Tyr13]VIP greater than [Tyr13]VIP greater than or equal to [Ser9]VIP greater than or equal to VIP(1-23)-PACAP(24-27)(VIP-PACAP) greater than VIP (vasoactive intestinal peptide). The N-terminal moiety of PACAP(1-27) was more important than the three amino acids at the C-terminus for 125I-PACAP(1-27)-binding site recognition. For rat pancreatic 125I-VIP-binding sites tested with 125I-VIP, the order of binding affinity was PACAP = PACAP(1-27) greater than or equal to VIP = [Ser9]VIP = [Tyr13]VIP = [Ser9,Try13]VIP greater than or equal to PACAP-VIP greater than or equal to VIP-PACAP greater than PACAP(2-38) = PACAP(2-27). Pancreatic 125I-VIP-binding sites, when compared to 125I-PACAP(1-27)-binding sites, showed little specificity and only weak coupling, so that PACAP and VIP-PACAP acted only as partial VIP agonists on adenylate cyclase.
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PMID:Structural requirements for the binding of the pituitary adenylate-cyclase-activating peptide to receptors and adenylate-cyclase activation in pancreatic and neuronal membranes. 199 28

We investigated the ability of two forms of Pituitary Adenylate Cyclase Activating Polypeptide [PACAP-38, the 38 amino acid peptide isolated from ovine hypothalamus, and PACAP-27, a shorter N-terminal (1-27) amidated version] to interact with specific receptors in membranes from the human neuroblastoma cell line NB-OK. [125I]PACAP-27 bound rapidly and specifically to one class of high affinity sites (Kd 0.5 nM). VIP inhibited [125I]PACAP-27 binding 300- to 1000-fold less potently than PACAP-27 and PACAP-38. One microM PHI prevented tracer binding only partially and secretin, glucagon and GRF(1-29)NH2 were ineffective in this respect. PACAP-27 and PACAP-38 stimulated adenylate cyclase activity dose dependently and with similar efficacy (Kact 0.2-0.3 nM), this activation being compatible with the occupancy of specific high affinity PACAP receptor. VIP was markedly less potent and less efficient on this enzyme than PACAP. Chemical cross-linking of [125I]PACAP-27 followed by SDS-PAGE and autoradiography revealed specific cross-linking with a 68 kDa protein.
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PMID:The novel VIP-like hypothalamic polypeptide PACAP interacts with high affinity receptors in the human neuroblastoma cell line NB-OK. 217 43

Sensitive and specific two-side enzyme immunoassays (two-site EIAs) for pituitary adenylate cyclase activating polypeptides, PACAP38, and PACAP27, have been established using six monoclonal antibodies against PACAP38, and a rabbit antibody against a C-terminal portion of PACAP27. In extracts of rat hypothalamus, these EIAs detected not only PACAP38 and PACAP27 but also an immunoreactive (ir-) PACAP lacking an epitope of a monoclonal antibody, PA-1C, which recognizes the C-terminal portion of PACAP38. By the use of these EIAs, it was found that one of the human neuroblastoma cell lines, IMR-32, produced ir-PACAP. In reverse-phase (RP-)HPLC, intracellular and extracellular ir-PACAPs were separated into two peaks, of which one was eluted at a position close to that of PACAP38 and the other in rather hydrophobic fractions. Those ir-PACAPs also lacked PA-1C epitope of PACAP38. SDS-PAGE and immunoblot analysis of the two peaks of the RP-HPLC indicated that they consisted of several components including those with apparent molecular weights of 6.5 k and 10 k for the first peak ir-PACAP, and 14 k and 20 k for the second peak ir-PACAP. These results indicate that IMR-32 produces a precursor of PACAP and related peptides generated in various processing steps. Although the significance of the modification in the C-terminus of PACAP38 is unknown, IMR-32 may be a cell line useful for studying the regulation of the biosynthesis of PACAP.
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PMID:Production of immunoreactive pituitary adenylate cyclase activating polypeptide (PACAP) by human neuroblastoma cells, IMR-32: detection and characterization with monoclonal and polyclonal antibodies against different epitopes of PACAP. 768 92

Pituitary adenylate cyclase activating peptide-38 (PACAP-38), PACAP-27 and vasoactive intestinal polypeptide (VIP) increased intracellular cAMP content in human neuroblastoma NB-OK-1 cells transiently. PACAP and VIP also arrested cell growth and induced morphological differentiation, which lasted for 24 h in spite of removal of PACAP-38 and PACAP-27. The order of potencies for the neurite outgrowth and the arrest of cell growth is PACAP-38 > PACAP-27 > VIP. The results suggest the possibility that these neuropeptides are new candidates for differentiation activity.
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PMID:Pituitary adenylate cyclase activating peptide and vasoactive intestinal polypeptide: differentiation effects on human neuroblastoma NB-OK-1 cells. 790 38

The effects of PACAPs on [Ca2+]i were compared to those of carbachol in human neuroblastoma NB-OK-1 cells. PACAP(1-27) and PACAP(1-38) increased [Ca2+]i in a biphasic manner: a transient rise and a secondary plateau. The transient phase reflected the mobilization of [Ca2+]i pool(s) via the inositol phosphate pathway. The modest sustained plateau required extracellular Ca2+. Carbachol also increased [Ca2+]i in a biphasic manner, but it mobilized intracellular Ca2+ pool(s) with a higher efficacy than PACAPs, then greatly increased Ca2+ entry, this being accompanied by a more marked and prolonged elevation of IP3 and IP4 than with PACAPs. It is likely that cAMP-mediated phosphorylations due to PACAPs facilitated desensitization at the PACAP receptor-phospholipase C level, so that there was less Ca2+ handling through PACAP receptors than with muscarinic M1 receptors.
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PMID:Contrasting effects of PACAP and carbachol on [Ca2+]i and inositol phosphates in human neuroblastoma NB-OK-1 cells. 813 91

Clonal human neuroblastoma cells SH-IN undergo a very conspicuous phenotypic change in culture. Large substrate-adherent cells with a slow growth rate give rise to small cells emerging in focal aggregates and growing to high cell densities. This is accompanied by a dramatic switch in the expression of receptors for the structurally related neuropeptides VIP (vasoactive intestinal polypeptide) and PACAP (pituitary adenylate cyclase activating polypeptide). Large cells expressed mainly PACAP-specific receptors that triggered stimulation of intracellular cGMP production. On the other hand, polyvalent VIP/PACAP receptors positively coupled to adenylate cyclase were mostly observed in the small cells. Both neuropeptides stimulated cell proliferation in large and small cells. These data, together with the previous demonstration of autocrine/paracrine actions of VIP and PACAP in human neuroblastomas, support the idea that these neuropeptides may participate in the establishment of the apparent phenotype in these cancer cells.
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PMID:Switches in the expression and function of PACAP and VIP receptors during phenotypic interconversion in human neuroblastoma cells. 891 56

Pituitary adenylate cyclase activating polypeptide type I receptor (PACAPr) belongs to the novel subfamily of the G-protein coupled receptors with a long extracellular N-terminus, which functions as a major binding site for the PACAP. Three different N-terminal fragments of rat PACAPr were overexpressed in Escherichia coli and purified using His-tags or maltose-binding protein as anchors for affinity chromatography. The purified and refolded proteins were used for the production and screening of monoclonal antibodies (MAbs) to PACAPr. Fifteen hybridoma cell lines producing MAbs specific to PACAPr were generated and characterized. Epitope analysis by competitive enzyme-linked immunoadsorbent assay (ELISA) indicated the presence of two groups of overlapping epitopes in the N-terminal fragment of PACAPr. Reactivity of MAbs with SDS-denaturated and native rat PACAPr was demonstrated by immunoblotting and flow cytometric analysis using transiently transfected COS cells and stably transfected CHO cells expressing rat PACAPr. Each antibody was examined by immunoblotting for the ability to cross react with the human PACAPr in human neuroblastoma NB-OK cells and most of them were shown to recognize human PACAPr as effectively as rat PACAPr. MAbs against the N-terminal extracellular domain of PACAPr can be used for the immunochemical study of the receptor-ligand interaction and for the investigation of PACAPr distribution in normal and tumor tissues.
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PMID:Production and characterization of monoclonal antibodies to pituitary adenylate cyclase activating polypeptide type I receptor. 1057 Dec 63

Expression of VPAC and PAC1 receptor isoforms was determined in six neuroblastoma cell lines as well as in human embryonic and adult brain using reverse transcriptase PCR and quantitative PCR. PAC1 receptor splice variants missing a 21 amino acid sequence in the amino terminal domain were found to be the major receptor variants in the neuroblastoma cell lines and also were highly expressed in embryonic brain compared to adult brain. In four of the neuroblastoma cell lines, VIP and PACAP stimulated cyclic AMP production with different potencies and levels of maximal stimulation. High potency and greatest maximal stimulation of cyclic AMP for each peptide were recorded in SH-SY5Y cells, indicating the presence of high affinity VIP and PACAP receptors. Further characterization of specific VPAC and PAC1 receptor isoforms was carried out in the SH-SY5Y cell line, where along with known PAC1 receptor splice variants and the VPAC2 receptor, a number of novel PAC1 receptor splice variants were identified. The comparatively low level expression of the VPAC2 receptor along with the poor responsiveness of SH-SY5Y cells to the VPAC2 receptor-specific agonist Ro 25-1553 indicated that this receptor did not contribute significantly to the observed VIP responses. When the individual PAC1 receptor isoforms were expressed in COS 7 cells, the ability of VIP to activate cyclic AMP production was increased more than 50-fold at the majority of the PAC1 receptor variants lacking the 21 amino acid amino terminal domain sequence compared to those with the complete domain. Smaller changes were seen in the potency of PACAP-38. Similar trends were seen with inositol phosphate responses, where in each case agonist potencies were lower than for cyclic AMP production. The results of this study show that the combination of different amino terminal and intracellular loop 3 splicing variants in the PAC1 receptor dictates the ability of agonists, particularly VIP, to activate signaling pathways. VIP has considerably greater potency at most PAC1 receptors with the short amino terminal domain, and these therefore may mediate physiological effects of both VIP and PACAP. Furthermore, there may be a phenotypic switch in the expression of different PAC1 receptor amino terminal splice variants between embryonic and mature nervous system, indicating that regulation of this event may have an important role in VIP/PACAP function, particularly in the developing nervous system.
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PMID:Characterization of novel splice variants of the PAC1 receptor in human neuroblastoma cells: consequences for signaling by VIP and PACAP. 1622 89


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