Biomaterial Database

Agonist regulation of cellular Gs alpha-subunit levels in neuroblastoma x glioma hybrid NG108-15 cells transfected to express different levels of the human beta 2 adrenoceptor. 1994

E J Adie, and G Milligan

Department of Biochemistry, University of Glasgow, Scotland, U.K.

Neuroblastoma x glioma hybrid NG108-15 cells endogenously express at least three receptors which activate adenylate cyclase via the intermediacy of the stimulatory G-protein, Gs. Sustained exposure of the cells to agonists at the IP prostanoid receptor results in a substantial decrease in cellular levels of the alpha-subunit of Gs (Gs alpha) [McKenzie and Milligan (1990) J. Biol. Chem. 265, 17084-17093; Adie, Mullaney, McKenzie and Milligan (1992) Biochem J. 285, 529-536]. By contrast, equivalent treatments of the cells with agonists at either the A2 adenosine receptor or the secretin receptor have no measurable effect on cellular amounts of Gs alpha. To examine whether this is a feature specific to the IP prostanoid receptor or is related to the level of expression of the individual receptors, NG108-15 cells were transfected with a construct containing a human beta 2-adrenoceptor cDNA under the control of the beta-actin promoter. Two clones of these cells were examined in detail, beta N22, which expressed some 4000 fmol/mg of membrane protein, and clone beta N17, which expressed approx. 300 fmol/mg of membrane protein of the receptor. Exposure of beta N22 cells to the beta-adrenergic agonist isoprenaline resulted maximally in some 55% decrease in membrane-associated levels of Gs alpha, without effect on membrane levels of Gi2 alpha, Gi3 alpha, G(o) alpha or Gq alpha/G11 alpha. Dose-response curves to isoprenaline in beta N22 cells indicated that half-maximal down-regulation of Gs alpha was produced by approx. 1 nM agonist. Equivalent exposure of beta N17 cells to isoprenaline did not significantly modify levels of any of the G-protein alpha subunits, including Gs alpha. In beta N22 cells the IP prostanoid receptor was expressed at similar levels to those in wild-type NG108-15 cells, and treatment with iloprost resulted in a similar down-regulation of cellular Gs alpha levels. Iloprost was also effective in causing down-regulation of Gs alpha levels in clone beta N17. Concurrent addition of both isoprenaline and iloprost to clone beta N22 resulted in less than additive down-regulation of Gs alpha. These results demonstrate that the phenomenon of agonist-induced specific G-protein down-regulation is determined by the levels of expression of the receptor.

UI	MeSH Term	Description	Entries
D007545	Isoproterenol	Isopropyl analog of EPINEPHRINE; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant.	Isoprenaline,Isopropylarterenol,4-(1-Hydroxy-2-((1-methylethyl)amino)ethyl)-1,2-benzenediol,Euspiran,Isadrin,Isadrine,Isopropyl Noradrenaline,Isopropylnoradrenaline,Isopropylnorepinephrine,Isoproterenol Hydrochloride,Isoproterenol Sulfate,Isuprel,Izadrin,Norisodrine,Novodrin,Hydrochloride, Isoproterenol,Noradrenaline, Isopropyl,Sulfate, Isoproterenol
D011943	Receptors, Adrenergic, beta	One of two major pharmacologically defined classes of adrenergic receptors. The beta adrenergic receptors play an important role in regulating CARDIAC MUSCLE contraction, SMOOTH MUSCLE relaxation, and GLYCOGENOLYSIS.	Adrenergic beta-Receptor,Adrenergic beta-Receptors,Receptors, beta-Adrenergic,beta Adrenergic Receptor,beta-Adrenergic Receptor,beta-Adrenergic Receptors,Receptor, Adrenergic, beta,Adrenergic Receptor, beta,Adrenergic beta Receptor,Adrenergic beta Receptors,Receptor, beta Adrenergic,Receptor, beta-Adrenergic,Receptors, beta Adrenergic,beta Adrenergic Receptors,beta-Receptor, Adrenergic,beta-Receptors, Adrenergic
D011982	Receptors, Prostaglandin	Cell surface receptors that bind prostaglandins with high affinity and trigger intracellular changes which influence the behavior of cells. Prostaglandin receptor subtypes have been tentatively named according to their relative affinities for the endogenous prostaglandins. They include those which prefer prostaglandin D2 (DP receptors), prostaglandin E2 (EP1, EP2, and EP3 receptors), prostaglandin F2-alpha (FP receptors), and prostacyclin (IP receptors).	Prostaglandin Receptors,Prostaglandin Receptor,Receptor, Prostaglandin,Receptors, Prostaglandins,Prostaglandins Receptors
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006822	Hybrid Cells	Any cell, other than a ZYGOTE, that contains elements (such as NUCLEI and CYTOPLASM) from two or more different cells, usually produced by artificial CELL FUSION.	Somatic Cell Hybrids,Cell Hybrid, Somatic,Cell Hybrids, Somatic,Cell, Hybrid,Cells, Hybrid,Hybrid Cell,Hybrid, Somatic Cell,Hybrids, Somatic Cell,Somatic Cell Hybrid
D012333	RNA, Messenger	RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.	Messenger RNA,Messenger RNA, Polyadenylated,Poly(A) Tail,Poly(A)+ RNA,Poly(A)+ mRNA,RNA, Messenger, Polyadenylated,RNA, Polyadenylated,mRNA,mRNA, Non-Polyadenylated,mRNA, Polyadenylated,Non-Polyadenylated mRNA,Poly(A) RNA,Polyadenylated mRNA,Non Polyadenylated mRNA,Polyadenylated Messenger RNA,Polyadenylated RNA,RNA, Polyadenylated Messenger,mRNA, Non Polyadenylated
D014162	Transfection	The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.	Transfections
D015398	Signal Transduction	The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.	Cell Signaling,Receptor-Mediated Signal Transduction,Signal Pathways,Receptor Mediated Signal Transduction,Signal Transduction Pathways,Signal Transduction Systems,Pathway, Signal,Pathway, Signal Transduction,Pathways, Signal,Pathways, Signal Transduction,Receptor-Mediated Signal Transductions,Signal Pathway,Signal Transduction Pathway,Signal Transduction System,Signal Transduction, Receptor-Mediated,Signal Transductions,Signal Transductions, Receptor-Mediated,System, Signal Transduction,Systems, Signal Transduction,Transduction, Signal,Transductions, Signal
D015536	Down-Regulation	A negative regulatory effect on physiological processes at the molecular, cellular, or systemic level. At the molecular level, the major regulatory sites include membrane receptors, genes (GENE EXPRESSION REGULATION), mRNAs (RNA, MESSENGER), and proteins.	Receptor Down-Regulation,Down-Regulation (Physiology),Downregulation,Down Regulation,Down-Regulation, Receptor
D015870	Gene Expression	The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.	Expression, Gene,Expressions, Gene,Gene Expressions