atrial-natriuretic-factor and Glioma

The effect of the natriuretic peptides ANP, BNP and CNP on cGMP formation and immediate early gene expression was investigated in PC12 phaeochromocytoma and C6 glioma cell lines. The three natriuretic peptides were shown to rapidly induce c-fos, TIS8/egr-1 and junB mRNA expression in both cell lines, via stimulation of the cGMP pathway. CNP stimulated cGMP formation and gene induction more potently than the other peptides in C6 cells, and this was statistically significant. In contrast, the three peptides produced similar gene induction in PC12 cells, despite the higher cGMP accumulation evoked by ANP or BNP. CNP was also found to increase DNA binding activity of the transcription factor AP1 in both cell types, demonstrating that natriuretic peptides potentially regulate key cellular gene expression.

Topics: Animals; Atrial Natriuretic Factor; Genes, Immediate-Early; Glioma; PC12 Cells; Pheochromocytoma; Rats; Tumor Cells, Cultured

The effect of endothelin-3 (ET-3) on C-type natriuretic peptide (CNP)-induced guanosine 3',5'-cyclic monophosphate (cGMP) was examined in C6 glioma cells, CNP-induced cGMP formation was both time- and dose-dependent, with an EC50 value of about 10 nM. While ET-3 and phorbol 12-myristate 13-acetate (PMA) had no effect on basal cGMP production, both compounds were potent inhibitors of CNP-induced cGMP formation, with IC50 values of approximately 10 and 2 nM, respectively. Although protein kinase C (PKC) inhibitors had no effect on basal cGMP formation, Ro 31-8220, a PKC inhibitor, reversed the ET-3 inhibition on CNP-induced cGMP formation by 63% and that of PMA almost completely. Our findings suggest that stimulation of cGMP formation by CNP in C6 glioma cells is negatively modulated by PKC activation, and that the inhibitory action of ET-3 on CNP-stimulated cGMP formation is mediated partly by PKC.

Topics: Animals; Atrial Natriuretic Factor; Cyclic GMP; Endothelin-3; Glioma; Natriuretic Peptide, C-Type; Proteins; Rats; Tumor Cells, Cultured

Cloned ANF-sensitive guanylyl cyclase (GC-A) and ANF-sensitive guanylyl cyclase from adrenal cortex differ in their sensitivity to the ANF analogs atriopeptin 1 and urodilatin. To test the hypothesis that these differences are due to different glycosylation, we investigated the effect of the N-glycosylation inhibitor tunicamycin on GC-A. Tunicamycin altered the response of GC-A to atriopeptin 1 and urodilatin, whereas the sensitivity to ANF remained unchanged. These data indicate that agonist specificities of different ANF-sensitive guanylyl cyclases are influenced by carbohydrate moieties.

Topics: Adrenal Cortex; Animals; Atrial Natriuretic Factor; Cell Line; Cell Membrane; Cloning, Molecular; Glioma; Glycosylation; Guanylate Cyclase; Kinetics; Molecular Weight; Peptide Fragments; Rats; Recombinant Proteins; Transfection; Tunicamycin

We studied the activity and the ultracytochemical localization of membrane-bound guanylate cyclase (GC) after stimulation with rat atrial natriuretic peptide (rANP), porcine brain natriuretic peptide (pBNP), rat brain natriuretic peptide (rBNP), or porcine C-type natriuretic peptide (CNP) in rat C6 glioma cells during proliferation or following exposure of confluent cells to dibutyryl cyclic AMP (db-cAMP) or retinoic acid (RA). Under our experimental conditions all peptides were activators of GC as demonstrated by the accumulation of cGMP within cells. During proliferation of C6 cells, the amounts of cGMP remained approximately constant. However, at subconfluency, confluency and postconfluency, the GC reaction product was located at different sites in C6 cells. At subconfluency, GC reaction product was on membranes of protoplasmic extensions, at postconfluency, GC reaction product was in association with membranes of cell bodies, and at confluency, both localizations of GC reaction product were detected. Incubation of confluent cells in culture medium containing db-cAMP or RA induced the appearance of long and slender protoplasmic extensions. Under these conditions, the GC reaction product was localized exclusively to these processes. These data suggest that GC is differentially located depending on the state of growth of glial cells, and that in differentiating glial cells GC is preferentially located in cell processes.

Topics: Animals; Atrial Natriuretic Factor; Bucladesine; Cell Division; Culture Media; Cyclic GMP; Glioma; Guanylate Cyclase; Guanylyl Imidodiphosphate; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Proteins; Rats; Swine; Tretinoin; Tumor Cells, Cultured

Receptor binding and cyclic GMP generation by three distinct natriuretic peptides (ANP, BNP, CNP) were studied in a cultured rat glioma cell line (C6). Binding studies revealed the presence of high-affinity binding sites for three natriuretic peptides with almost comparable affinities. In contrast, CNP and BNP were almost equipotent in stimulating intracellular cyclic GMP generation over the low concentration range, but CNP caused further elevation in the high concentration range, whereas ANP was minimally effective. Our data suggest that the glioma cells possess receptors more responsive to CNP than ANP and BNP despite no apparent correlation between receptor binding affinities and cyclic GMP responses.

Topics: Animals; Atrial Natriuretic Factor; Binding Sites; Cyclic GMP; Glioma; Natriuretic Peptide, Brain; Natriuretic Peptide, C-Type; Nerve Tissue Proteins; Rats; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface; Tumor Cells, Cultured

HS-142-1 is a novel non-peptide antagonist for atrial natriuretic peptide (ANP) receptor. The effect of HS-142-1 on the cyclic GMP production elicited by natriuretic peptides in neuronal cell lines, PC12 and NG108-15 was examined. Natriuretic peptides such as ANP, brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) enhanced cyclic GMP production in a dose-dependent manner. HS-142-1 inhibited cyclic GMP accumulation elicited by natriuretic peptides in a dose-dependent fashion in both cells. The results suggest that HS-142-1 will be an important tool for identification and understanding of the mechanisms by which natriuretic peptides act in nervous systems.

Topics: Animals; Atrial Natriuretic Factor; Cell Line; Cyclic GMP; Dose-Response Relationship, Drug; Glioma; Hybrid Cells; Kinetics; Mice; Neuroblastoma; PC12 Cells; Polysaccharides; Rats

Characterization of the serotonin (5-HT)-induced cyclic GMP (cGMP) elevation was investigated in comparison with bradykinin- and ANP-induced elevations in NG108-15 cells. At 20 s, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester (BAPTA-AM, 100 microM), a membrane-permeabilized Ca2+ chelator, or N-monomethyl-L-arginine (NMMA, 300 microM), an inhibitor of L-arginine-derived nitric oxide (NO) synthesis, inhibited 5-HT-induced elevation by approximately 40%, and completely inhibited bradykinin-induced response. Neither 5-HT- nor ANP-induced cGMP elevation at 10 min was affected by BAPTA-AM or NMMA. The cGMP elevated by 5-HT as well as by ANP was effluxed to the extracellular medium. These results and our previous report suggest that 5-HT stimulates two subtypes of 5-HT receptors in NG108-15: first, 5-HT3 subtype stimulating Ca(2+)-sensitive cytosolic guanylate cyclase through NO derived from L-arginine and second, a probably novel 5-HT receptor subtype involved in activation of membrane-bound guanylate cyclase.

Topics: Animals; Atrial Natriuretic Factor; Bradykinin; Cell Line; Cell Membrane; Chelating Agents; Cyclic GMP; Egtazic Acid; Glioma; Guanylate Cyclase; Hybrid Cells; Kinetics; Neuroblastoma; Receptors, Serotonin; Serotonin

Atrial natriuretic factors (ANFs) were tested for their effects on cyclic GMP production in two neurally derived cell lines, the C6-2B rat glioma cells and the PC12 rat pheochromocytoma cells. These cell lines were selected because both are known to possess high amounts of the particulate form of guanylate cyclase, a proposed target of ANF in peripheral organs. Previous studies from our laboratory have shown that ANF selectively activates particulate, but not soluble, guanylate cyclase in homogenates of a variety of rat tissues and that one class of ANF receptor appears to be the same glycoprotein as particulate guanylate cyclase. In the present study we found that four analogs of ANF stimulate cyclic GMP accumulation in both C6-2B and PC12 cells with the rank order of potency being atriopeptin III = atriopeptin II greater than human atrial natriuretic polypeptide greater than atriopeptin I. Atriopeptin II (100 nM) for 20 min elevated cyclic GMP content in C6-2B cells fourfold and in PC12 cells 12-fold. Atriopeptin II (100 nM) for 20 min also stimulated the efflux of cyclic GMP from both C6-2B cells (47-fold) and PC12 cells (12-fold). Accumulation of cyclic GMP in both cells and media was enhanced by preincubation with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (250 microM). After 20 min of exposure to atriopeptin II, cyclic GMP amounts in the media were equal to or greater than the amounts in the cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 1-Methyl-3-isobutylxanthine; Adrenal Gland Neoplasms; Animals; Atrial Natriuretic Factor; Cell Line; Cyclic GMP; Dose-Response Relationship, Drug; Glioma; Pheochromocytoma; Rats; Time Factors

Atrial natriuretic hormones (ANHs) applied to polyploid rat glioma cells induced hyperpolarizations of about 30 s duration, followed by depolarizations lasting 1-2 min. Repeated applications of the peptide resulted in desensitization. The reversal potential of -87 mV at an extracellular K+ concentration of 5 mM and the decrease of membrane resistance during the hyperpolarization indicate that K+ channels were activated by ANH. In these cells the fluorescence signal of 2-[(2-bis[carboxymethyl]amino-5-methylphenoxy)-methyl]-6-methoxy-8-bis [carboxymethyl]aminoquinoline (quin2) was not affected by ANH suggesting that ANH did not change the cytosolic Ca2+-activity.

Topics: Animals; Atrial Natriuretic Factor; Bradykinin; Cells, Cultured; Glioma; Hybrid Cells; Ion Channels; Membrane Potentials; Nerve Tissue; Neuroblastoma; Potassium; Rats

Atriopeptin III and related atrial natriuretic peptide hormones strongly elevate the level of cyclic GMP in three neural tumor cell lines. At peptide concentrations of 1 microM clear-cut plateaus of the dose-response curves are not yet reached. Atriopeptin III increases the intracellular concentration of cyclic GMP to a maximum in the course of 30-40 min. The effect of atriopeptin III on the cellular cyclic GMP level is independent of the concentration of extracellular Ca2+ and is not affected by the Ca2+ ionophore A23187. These results suggest (1) that atrial natriuretic hormones may play an important role in the nervous system, and (2) that cultured neural cells may be useful tools in the elucidation of the mechanisms of action of these hormones.

Topics: 1-Methyl-3-isobutylxanthine; Animals; Atrial Natriuretic Factor; Calcimycin; Calcium; Cell Line; Cyclic GMP; Glioma; Hybrid Cells; Kinetics; Neuroblastoma; Rats

Topics: Animals; Atrial Natriuretic Factor; Calcium; Cells, Cultured; Glioma; Membrane Potentials; Rats