A novel cholera toxin‐sensitive G‐protein (G<sub>c</sub>) regulating receptor‐mediated phosphoinositide signalling in human pituitary clonal cells

Lo, William W.Y.; Hughes, J.

doi:10.1016/0014-5793(87)80840-2

Cited by 38 publications

(11 citation statements)

References 21 publications

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“…On the other hand, PTX had no effect on carbachol-stimulated PI hydrolysis, indicating that the effect of the cloned Ml receptors on PI hydrolysis is not mediated via coupling to PTX-sensitive G-proteins. The inability of such G-proteins to mediate muscarinic PI effects is in line with findings from studies conducted on mAChR from tissues and cell lines (Masters et al, 1985;Harden et al, 1986;Lo and Hughes, 1987 (Fukuda et al, 1987).…”

Section: Resultssupporting

confidence: 63%

Cloned M1 muscarinic receptors mediate both adenylate cyclase inhibition and phosphoinositide turnover.

1988

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The rat Ml muscarinic receptor gene was cloned and expressed in a rat cell line lacking endogenous muscarinic receptors. Assignment of the cloned receptors to the Ml class was pharmacologically confirmed by their high affimity for the Mi- possesses its own distinctive characteristics, such as coupling to a specific effector system or G-protein. Previous studies do not provide an answer to these questions because of the presence of mutliple receptor subtypes in the experimental material. Characterization of the molecular properties of the M 1 muscarinic receptor subtype presents special difficulties because of the lack of tissues or cell lines which express the MI receptor subtype exclusively. For example, the cerebral cortex, used in the past for studies on the MI subtype, was found to contain M3 and M4 subtypes as well Peralta et al., 1987). Furthermore, the selective muscarinic antagonist pirenzepine (PZ), which distinguishes between the M1 and M2 subtypes, does not adequately distinguish between MI, M3 and M4. In order to determine the pharmacological and biochemical effects of the MI subtype, material containing purely MI is required.Recently, the porcine M2 receptor subtype was cloned and stably expressed in cells that lack endogenous mAChRs. The pharmacological properties of the single recombinant M2 receptor subtype were found to be identical with those of M2 muscarinic receptor subtype from conventional sources. Furthermore, the recombinant receptor was found to be coupled to both AC inhibition and PI turnover . In the present work we cloned and stably expressed the M 1 muscarinic receptor subtype gene in a rat cell line, RAT-1, in order to study its molecular responses. We describe here the pharmacological and biochemical properties of the cloned Ml receptors, and show that they are coupled to G-protein and mediate both AC inhibition and PI hydrolysis.

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Section: Resultssupporting

confidence: 63%

Cloned M1 muscarinic receptors mediate both adenylate cyclase inhibition and phosphoinositide turnover.

1988

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“…Direct interaction of the CT-activated G, protein with phospholipase C could also be a possible explanation for the observed inhibition of IP3 production. This is however unlikely, as VIP, which stimulates adenylate cyclase but not phospholipase C [14], had no effect on CCK-OP-induced stimulation of phospholipase C. Since GTPyS-induced IPs production is also inhibited by CT, we assume that inhibition of phospholipase C is due to ADP-ribosylation of a G-protein which couples the CCK-receptor to phospholipase C, leading to functional inactivation of this G-protein and not to inhibition of receptor-G-protein interaction as has been assumed by Lo and Hughes [16] for pituitary Flow 9000 cells.…”

Section: Discussionmentioning

confidence: 85%

Acetylcholine and cholecystokinin receptors functionally couple by different G‐proteins to phospholipase C in pancreatic acinar cells

et al. 1988

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We have studied the involvement of GTP-binding proteins in the stimulation of phospholipase C from rat pancreatic acinar cells. Pretreatment of permeabilized cells with activated cholera toxin inhibited both cholecystokinin-octapeptide (CCK-OP) and GTPyS but not carbachol (CCh)-induced production of inositol trisphosphate. Pertussis toxin had no effect. Neither vasoactive intestinal polypeptide, a stimulator, of adenylyl cyclase, nor the CAMP-analogue, 8-bromo CAMP, mimicked the inhibitory effect of cholera toxin on agonist-induced phospholipase C activation. This indicates that inhibition by cholera toxin could not be attributed to a direct interaction of cholera toxin activated G, with phospholipase C or to an elevation of CAMP. In isolated rat pancreatic plasma membranes cholera toxin ADP-ribosylated a 40 kDa protein, which was inhibited by CCK-OP but not by CCh. We conclude from these data that both CCK-and muscarinic acetylcholine receptors functionally couple to phospholipase C by two different GTP-binding proteins.

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“…There are reports that a cholera toxin-sensitive and pertussis toxin-insensitive G protein is involved in the inositol phospholipid hydrolysis in a human pituitary cell line (44) and in a human T-lymphocyte line (45). It is not known whether G,, protein is ADP-ribosylated in the presence of cholera toxin, although it possesses an arginine residue at amino acid position 179.…”

Section: Discussionmentioning

confidence: 99%

Sequence analysis of cDNA and genomic DNA for a putative pertussis toxin-insensitive guanine nucleotide-binding regulatory protein alpha subunit.

Matsuoka

Itoh

Kozasa

et al. 1988

Proc. Natl. Acad. Sci. U.S.A.

195

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We have isolated cDNA clones from rat C6 glioma cells coding for several guanine nucleotide-binding regulatory protein (G protein) a subunits (G.). The cDNA clones were then used to isolate human chromosomal genes. Among human genomic clones isolated by cross-hybridization with the rat cDNA for the a subunit of the inhibitory G protein G,2, termed Go, a clone designated AHGi62 was found to contain a sequence that is highly homologous but distinct from any ofthe known G. sequences, and we have tentatively designated this sequence G. The amino acid sequence of rat Gx. shows 66% and 40% similarity with rat Go and rat G. (the a subunit of the stimulatory G protein), respectively. By RNA blot hybridization analysis, mRNA of =3.2 kilobases was detected mainly in brain.

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A novel cholera toxin‐sensitive G‐protein (G_c) regulating receptor‐mediated phosphoinositide signalling in human pituitary clonal cells

Cited by 38 publications

References 21 publications

Cloned M1 muscarinic receptors mediate both adenylate cyclase inhibition and phosphoinositide turnover.

Cloned M1 muscarinic receptors mediate both adenylate cyclase inhibition and phosphoinositide turnover.

Acetylcholine and cholecystokinin receptors functionally couple by different G‐proteins to phospholipase C in pancreatic acinar cells

Sequence analysis of cDNA and genomic DNA for a putative pertussis toxin-insensitive guanine nucleotide-binding regulatory protein alpha subunit.

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A novel cholera toxin‐sensitive G‐protein (Gc) regulating receptor‐mediated phosphoinositide signalling in human pituitary clonal cells

Cited by 38 publications

References 21 publications

Cloned M1 muscarinic receptors mediate both adenylate cyclase inhibition and phosphoinositide turnover.

Cloned M1 muscarinic receptors mediate both adenylate cyclase inhibition and phosphoinositide turnover.

Acetylcholine and cholecystokinin receptors functionally couple by different G‐proteins to phospholipase C in pancreatic acinar cells

Sequence analysis of cDNA and genomic DNA for a putative pertussis toxin-insensitive guanine nucleotide-binding regulatory protein alpha subunit.

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A novel cholera toxin‐sensitive G‐protein (G_c) regulating receptor‐mediated phosphoinositide signalling in human pituitary clonal cells