NG108-15 Neuroblastoma-glioma Hybrid Cells Research Articles

Bradykinin-activated transmembrane signals are coupled via No or Ni to production of inositol 1,4,5-trisphosphate, a second messenger in NG108-15 neuroblastoma-glioma hybrid cells.

The addition of bradykinin to NG108-15 cells results in a transient hyperpolarization followed by prolonged cell depolarization. Injection of inositol 1,4,5-trisphosphate or Ca2+ into the cytoplasm of NG108-15 cells also elicits cell hyperpolarization followed by depolarization. Tetraethylammonium ions inhibit the hyperpolarizing response of cells to bradykinin or inositol 1,4,5-trisphosphate. Thus, the hyperpolarizing phase of the cell response may be due to inositol 1,4,5-trisphosphate-dependent release of stored Ca2+ into the cytoplasm, which activates Ca2+-dependent K+ channels. The depolarizing phase of the cell response to bradykinin is due largely to inhibition of M channels, thereby decreasing the rate of K+ efflux from cells and, to a lesser extent, to activation of Ca2+-dependent ion channels and Ca2+ channels. In contrast, injection of inositol 1,4,5-trisphosphate or Ca2+ into the cytosol did not alter M channel activity. Incubation of NG108-15 cells with pertussis toxin inhibits bradykinin-dependent cell hyperpolarization and depolarization. Bradykinin stimulates low Km GTPase activity and inhibits adenylate cyclase in NG108-15 membrane preparations but not in membranes prepared from cells treated with pertussis toxin. Reconstitution of NG108-15 membranes from cells treated with pertussis toxin with nanomolar concentrations of a mixture of highly purified No and Ni [guanine nucleotide-binding proteins that have no known function (No) or inhibit adenylate cyclase (Ni)] restores bradykinin-dependent activation of GTPase and inhibition of adenylate cyclase. These results show that [bradykinin . receptor] complexes interact with No or Ni and suggest that No and/or Ni mediate the transduction of signals from bradykinin receptors to phospholipase C and adenylate cyclase.

Purification of the opiate receptor of NG108-15 neuroblastoma-glioma hybrid cells.

Opiate receptors from NG108-15 neuroblastoma-glioma hybrid cell membranes were purified to apparent homogeneity in a form covalently labeled with the opiate affinity ligand 3-methylfentanylisothiocyanate (super-FIT). The purification procedure consists of five steps: quantitative labeling of opiate receptors in membranes with super-FIT; solubilization in a lubrol/3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate mixture; adsorption to and elution from a wheat germ agglutinin-Sepharose column; immunoaffinity chromatography on columns of immobilized anti-fentanyl; preparative gel electrophoresis in the presence of NaDodSO4. The protein was purified approximately 30,000-fold in 3% overall yield to a state in which there is 1 mol of super-FIT bound per mol of protein, corresponding to 21,000 pmol per mg of protein, the theoretically expected specific activity. The protein is glycosylated and migrates on NaDodSO4 gel electrophoresis with a Mr near 58,000. It has a strong tendency to dimerize, even in the presence of denaturing detergents, and it exists primarily as an oligomer in nondenaturing detergents.

Desensitization of PGE 1 receptors in neuroblastoma-glioma hybrid cells

Prostaglandin E 1 receptor sites were measured in homogenates of NG108-15 neuroblastoma-glioma hybrid cells after exposure of intact cells to PGE 1. Scatchard analysis of competitive binding studies showed that incubation of NG108-15 cells in the presence of 2.5 μM PGE 1 for 16 h resulted in a loss of PGE 1 receptors and an increase in the dissociation constant of the remaining receptors. Thus, cells challenged with PGE 1 not only lose adenylate cyclase activity, but also lose PGE 1 receptors and decreased the affinity of the remaining receptors for PGE 1.

Source and target cell specificities of a conditioned medium factor that increases choline acetyltransferase activity in cultured spinal cord cells

A macromolecular factor(s) in muscle conditioned medium (CM), when applied to spinal cord (SC) cells in culture, causes large increases in the activity of choline acetyltransferase (CAT), the enzyme which synthesizes the neurotransmitter acetylcholine. We have found apparent specificity of both species and cell type for the production, release, or action of this CAT stimulation component (CSC). Rat and mouse muscle CMs contained CSC which was active in mouse SC cells; chick muscle CM did not. In addition to muscle CM, the CM from cell cultures of mouse heart, liver, and kidney contained CSC. However, CM from secondary cultures of liver cells contained little if any CSC. These apparent specificities were not due to differences in the protein content of either the cells providing CM or of the CM itself. There was also apparent specificity of response to CSC among cholinergic cells in culture. Cultures of cells from only two of four regions of the mouse central nervous system, and from one of five neuronal cell lines tested, had increased CAT activity after treatment with muscle CM. The response in NG108-15 neuroblastoma-glioma hybrid cells was further characterized, and was used to develop a more convenient and rapid assay for CSC.