angiotensin-i and Neuroblastoma

A major portion of renin-like activity in extracts of brain tissues is due to nonspecific action of proteases. True renin has been separated from the proteases by various affinity chromatographic methods and true renin was identified by its inhibition by specific antirenin antibodies. Brain renin has been purified to varying extents. Renin in bovine pituitary was completely purified. Certain properties of brain renin are different from renal renin. The presence of inactive prorenin was also found in many regions. Immunohistochemical studies with renin antibodies showed intracellular localization of renin in many regions of the brain. Renin was also localized in LH gonadotrophs in the adenohypophysis. Many cloned neuroblastoma cell lines contain not only renin but also all other components of the renin-angiotensin system, indicating the existence of an intracellular mechanism of angiotensin formation within neurons.

Topics: Angiotensin I; Angiotensin II; Animals; Antibodies; Brain; Cathepsin D; Cathepsins; Cell Line; Chemical Phenomena; Chemistry, Physical; Chromatography, Affinity; Histocytochemistry; Hydrogen-Ion Concentration; Hypertension; Immunologic Techniques; Mice; Nephrectomy; Neuroblastoma; Rats; Renin; Tissue Distribution

Three children with renal hypertension are described. Two had histories of neuroblastoma treated by surgical resection and chemotherapy. They both presented later with unilateral atrophic kidney and marked hypertension. Only the child with severe cardiac failure demonstrated high plasma brain natriuretic peptide (BNP) concentrations. The remaining patient had a history of chronic nephritis treated with continuous ambulatory peritoneal dialysis. She also had chronic hypertension and severe cardiac failure. This child demonstrated high plasma BNP levels. The endogenous secretion of BNP is not triggered by hypertension alone, even though exogenous BNP has the pharmacological effect of reducing renin activity.

Topics: Adolescent; Angiotensin I; Angiotensin II; Atrophy; Blood Pressure; Child; Child, Preschool; Female; Heart Failure; Humans; Hypertension, Renal; Kidney; Male; Natriuretic Peptide, Brain; Neuroblastoma; Renin; Ventricular Function, Left

The effects of angiotensin II (AII) and related peptides on the mobilization of internal Ca2+ were studied in a subclone of NG 108-15 cells. The subclone, C1, was prepared by fluorescence-activated cell cloning using a rapid response kinetics and a large response magnitude following stimulation by AII as the selection criteria. Angiotensin I, AII, and angiotensin III (AIII) stimulated Ca2+ mobilization in the C1 cells in a concentration-dependent manner (1 nM-100 microM), yielding EC50 values of 437 +/- 80 nM (n = 4; slope = 1.6 +/- 0.3), 57 +/- 8 nM (n = 12; slope = 1.5 +/- 0.3), and 36 +/- 5 nM (n = 7; slope = 1.4 +/- 0.3), respectively. AIII was significantly more potent than AII (p less than 0.05). In contrast, Des-Phe8-AII, AII-hexapeptide (AII 3-8), and p-NH2-Phe6-AII (1-10 microM) were inactive as agonists. Although the effects of AII and AIII in C1 and parent NG108-15 cells were totally inhibited by the AT1 receptor-selective nonpeptide antagonist, DUP-753 (0.3-1 microM), the AT2-selective antagonists, EXP-655 and CGP42112A (1-10 microM), failed to block the effects of AII. DUP-753 (0.3-100 nM) produced dextral shifts of the AII-induced concentration-response curves and yielded an estimated affinity constant (pA2) of 8.5 +/- 0.2 (n = 16) using single-point analysis involving different concentrations of DUP-753. These data compared well with those obtained for the inhibition of AII-induced aortic contractions by DUP-753 (pA2 = 8.5) reported previously by others.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Angiotensin I; Angiotensin II; Angiotensin III; Angiotensin Receptor Antagonists; Animals; Biphenyl Compounds; Calcium; Imidazoles; Intracellular Membranes; Losartan; Neuroblastoma; Receptors, Angiotensin; Tetrazoles; Tumor Cells, Cultured

The murine neuroblastoma N1E-115 cell line contains binding sites for the angiotensin II (Ang II) receptor antagonist 125I-[Sarc1,Ile8]-Ang II (125I-SARILE). Binding of 125I-SARILE to N1E-115 membranes was rapid, reversible, and specific for Ang II-related peptides. The rank order potency of 125I-SARILE binding was the following: [Sarc1]-Ang II = [Sarc1,Ile8]-Ang II greater than Ang II greater than Ang III = [Sarc1,Thr8]-Ang II much greater than Ang I. Scatchard analysis of membranes prepared from confluent monolayers revealed a homogenous population of high affinity (KD = 383 +/- 60 pM) binding sites with a Bmax of 25.4 +/- 1.6 fmol/mg of protein. Moreover, the density, but not the affinity, of the binding sites increased as the cells progressed from logarithmic to stationary growth in culture. Finally, agonist, but not antagonist, binding to N1E-115 cells was regulated by guanine nucleotides. Collectively, these results suggest that the murine neuroblastoma N1E-115 cell line may provide a useful model in which to investigate the signal transduction mechanisms utilized by neuronal Ang II receptors.

Topics: 1-Sarcosine-8-Isoleucine Angiotensin II; Angiotensin I; Angiotensin II; Angiotensin III; Angiotensin Receptor Antagonists; Animals; Binding, Competitive; Cell Division; Cell Membrane; Guanylyl Imidodiphosphate; Kinetics; Mice; Neuroblastoma; Receptors, Angiotensin; Tumor Cells, Cultured

A kinetic analysis of the tyrosine-specific protein kinase of pp60c-src from the C1300 mouse neuroblastoma cell line Neuro-2A and pp60c-src expressed in fibroblasts was carried out to determine the nature of the increased specific activity of the neuroblastoma enzyme. In immune-complex kinase assays with ATP-Mn2+ and the tyrosine-containing peptide angiotensin I as phosphoacceptor substrate, pp60c-src from the neuroblastoma cell line was characterized by a maximum velocity (Vmax.) that was 7-15-fold greater than the Vmax. of pp60c-src from fibroblasts. The neuroblastoma enzyme exhibited Km values for ATP (16 +/- 3 microM) and angiotensin I (6.8 +/- 2.6 mM) that were similar to Km values for ATP (25 +/- 3 microM) and angiotensin I (6.5 +/- 1.7 mM) of pp60c-src from fibroblasts. pp60v-src expressed in Rous-sarcoma-virus-transformed cells exhibited an ATP Km value (25 +/- 4 microM) and an angiotensin I Km value (6.6 +/- 0.5 mM) that approximated the values determined for pp60c-src in neuroblastoma cells and fibroblasts. These results indicate that the pp60c-src kinase from neuroblastoma cells has a higher turnover number than pp60c-src kinase from fibroblasts, and that the neural form of the enzyme would be expected to exhibit increased catalytic activity at the saturating concentrations of ATP that are found intracellularly.

Topics: Adenosine Triphosphate; Angiotensin I; Animals; Cell Line; Enzyme Activation; Fibroblasts; Immunoelectrophoresis; Kinetics; Mice; Neuroblastoma; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Tumor Cells, Cultured

Topics: Angiotensin I; Angiotensin II; Angiotensin III; Angiotensins; Animals; Clone Cells; Cyclic GMP; Mice; Neuroblastoma; Neurons; Receptors, Angiotensin

Cells of the homogeneous hybrid line neuroblastoma x glioma (NG108-15) have many neuronal properties. Immunocytochemical tests show that they contain both immunoreactive renin and angiotensin; direct radioimmunoassays show that they are positive for renin, angiotensin I, and angiotensin II; enzymatic assays show that they contain angiotensinogen and converting enzyme as well. The renin appears to be present in an enzymatically inactive form that can be activated by trypsin and then blocked by antiserum to purified mouse submaxillary renin. Renin concentration and activity are increased by enhancing cellular differentiation with dibutyryl cyclic adenosine monophosphate or by serum withdrawal. These findings demonstrate a complete renin-angiotensin system within these neuron-like cells, and suggest that activation of intracellular renin could generate angiotensin II.

Topics: Angiotensin I; Angiotensin II; Angiotensins; Animals; Cell Line; Cricetinae; Glioma; Hybrid Cells; Mice; Neuroblastoma; Peptidyl-Dipeptidase A; Radioimmunoassay; Rats; Renin

The mechanism of formation of various peptide hormones in neuronal cells in the brain is not clear. The question of whether brain angiotensin II is formed by an extracellular mechanism as in the peripheral system or by an intracellular mechanism can be answered by using cloned cells in culture. We have screened several neuroblastoma cell lines of rat and mouse origin and found at least three cell lines that contain renin (EC 3.4.99.19), angiotensin-converting enzyme (dipeptidyl carboxypeptidase; peptidyldipeptide hydrolase, EC 3.4.15.1), and angiotensins I and II. This finding was interpreted to indicate that in these cells angiotensin formation takes place by an intracellular mechanism, in contrast to the extracellular mechanism well known to occur in plasma. This study also demonstrates the existence of viable and cloned cell lines that produce renin.

Topics: Angiotensin I; Angiotensin II; Angiotensins; Animals; Cell Line; Clone Cells; Hydrogen-Ion Concentration; Kinetics; Mice; Neoplasms, Experimental; Neuroblastoma; Peptidyl-Dipeptidase A; Rats; Renin; Species Specificity