Regulation of hepatocyte adenylate cyclase by amylin and CGRP: a single receptor displaying apparent negative cooperativity towards CGRP and simple saturation kinetics for amylin, a requirement for phosphodiesterase inhibition to observe elevated hepatocyte cyclic AMP levels and the phosphorylation of Gi‐2

Miles D. Houslay*, Nicholas J. Morris, Anne Savage, Alison Marker, Mark Bushfield

*Corresponding author for this work

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Challenge of intact hepatocytes with amylin only succeeded in elevating intracellular cyclic AMP levels and activating phosphorylase in the presence of the cAMP phosphodiesterase inhibitor IBMX. Both amylin and CGRP similarly activated adenylate cyclase, around 5‐fold, although ∼ 400‐fold higher levels of amylin were required to elicit half maximal activation. Amylin activated adenylate cyclase though apparently simple Michaelin kinetics whereas CGRP elicited activation by kinetics indicative of apparent negative co‐operativity. Use of the antagonist CGPP(8–37) showed that both CGRP and amylin activated hepatocyte adenylate cyclase through a common receptor by a mnemonical mechanism where it was proposed that the receptor co‐existed in interconvertible high and low affinity states for CGRP. It is suggested that this model may serve as a paradigm for G‐protein linked receptors in general. Amylin failed to both stimulate inositol phospholipid metabolism in hepatocytes and to elicit the desensitization of glucagon‐stimulated adenylate cyclase. Amylin did, however, elicit the phosphorylation of the inhibitory guanine nucleotide regulatory protein Gi‐2 in hepatocytes and prevented the action of insulin in reducing the level of phosphorylation of this G‐protein.

Original languageEnglish
Pages (from-to)66-82
Number of pages17
JournalJournal of Cellular Biochemistry
Volume55
Issue numberS1994A
DOIs
Publication statusPublished - 1994
Externally publishedYes

Fingerprint

Islet Amyloid Polypeptide
Phosphorylation
Phosphoric Diester Hydrolases
Adenylyl Cyclases
Cyclic AMP
Hepatocytes
Kinetics
Chemical activation
1-Methyl-3-isobutylxanthine
Phosphorylases
Phosphodiesterase Inhibitors
Phosphatidylinositols
GTP-Binding Proteins
Metabolism
Insulin

Cite this

@article{edcd6b5981e74020be5b9b184bf46874,
title = "Regulation of hepatocyte adenylate cyclase by amylin and CGRP: a single receptor displaying apparent negative cooperativity towards CGRP and simple saturation kinetics for amylin, a requirement for phosphodiesterase inhibition to observe elevated hepatocyte cyclic AMP levels and the phosphorylation of Gi‐2",
abstract = "Challenge of intact hepatocytes with amylin only succeeded in elevating intracellular cyclic AMP levels and activating phosphorylase in the presence of the cAMP phosphodiesterase inhibitor IBMX. Both amylin and CGRP similarly activated adenylate cyclase, around 5‐fold, although ∼ 400‐fold higher levels of amylin were required to elicit half maximal activation. Amylin activated adenylate cyclase though apparently simple Michaelin kinetics whereas CGRP elicited activation by kinetics indicative of apparent negative co‐operativity. Use of the antagonist CGPP(8–37) showed that both CGRP and amylin activated hepatocyte adenylate cyclase through a common receptor by a mnemonical mechanism where it was proposed that the receptor co‐existed in interconvertible high and low affinity states for CGRP. It is suggested that this model may serve as a paradigm for G‐protein linked receptors in general. Amylin failed to both stimulate inositol phospholipid metabolism in hepatocytes and to elicit the desensitization of glucagon‐stimulated adenylate cyclase. Amylin did, however, elicit the phosphorylation of the inhibitory guanine nucleotide regulatory protein Gi‐2 in hepatocytes and prevented the action of insulin in reducing the level of phosphorylation of this G‐protein.",
author = "Houslay, {Miles D.} and Morris, {Nicholas J.} and Anne Savage and Alison Marker and Mark Bushfield",
year = "1994",
doi = "10.1002/jcb.240550008",
language = "English",
volume = "55",
pages = "66--82",
journal = "Journal of Cellular Biochemistry",
issn = "0730-2312",
publisher = "Wiley-Liss Inc.",
number = "S1994A",

}

TY - JOUR

T1 - Regulation of hepatocyte adenylate cyclase by amylin and CGRP

T2 - a single receptor displaying apparent negative cooperativity towards CGRP and simple saturation kinetics for amylin, a requirement for phosphodiesterase inhibition to observe elevated hepatocyte cyclic AMP levels and the phosphorylation of Gi‐2

AU - Houslay, Miles D.

AU - Morris, Nicholas J.

AU - Savage, Anne

AU - Marker, Alison

AU - Bushfield, Mark

PY - 1994

Y1 - 1994

N2 - Challenge of intact hepatocytes with amylin only succeeded in elevating intracellular cyclic AMP levels and activating phosphorylase in the presence of the cAMP phosphodiesterase inhibitor IBMX. Both amylin and CGRP similarly activated adenylate cyclase, around 5‐fold, although ∼ 400‐fold higher levels of amylin were required to elicit half maximal activation. Amylin activated adenylate cyclase though apparently simple Michaelin kinetics whereas CGRP elicited activation by kinetics indicative of apparent negative co‐operativity. Use of the antagonist CGPP(8–37) showed that both CGRP and amylin activated hepatocyte adenylate cyclase through a common receptor by a mnemonical mechanism where it was proposed that the receptor co‐existed in interconvertible high and low affinity states for CGRP. It is suggested that this model may serve as a paradigm for G‐protein linked receptors in general. Amylin failed to both stimulate inositol phospholipid metabolism in hepatocytes and to elicit the desensitization of glucagon‐stimulated adenylate cyclase. Amylin did, however, elicit the phosphorylation of the inhibitory guanine nucleotide regulatory protein Gi‐2 in hepatocytes and prevented the action of insulin in reducing the level of phosphorylation of this G‐protein.

AB - Challenge of intact hepatocytes with amylin only succeeded in elevating intracellular cyclic AMP levels and activating phosphorylase in the presence of the cAMP phosphodiesterase inhibitor IBMX. Both amylin and CGRP similarly activated adenylate cyclase, around 5‐fold, although ∼ 400‐fold higher levels of amylin were required to elicit half maximal activation. Amylin activated adenylate cyclase though apparently simple Michaelin kinetics whereas CGRP elicited activation by kinetics indicative of apparent negative co‐operativity. Use of the antagonist CGPP(8–37) showed that both CGRP and amylin activated hepatocyte adenylate cyclase through a common receptor by a mnemonical mechanism where it was proposed that the receptor co‐existed in interconvertible high and low affinity states for CGRP. It is suggested that this model may serve as a paradigm for G‐protein linked receptors in general. Amylin failed to both stimulate inositol phospholipid metabolism in hepatocytes and to elicit the desensitization of glucagon‐stimulated adenylate cyclase. Amylin did, however, elicit the phosphorylation of the inhibitory guanine nucleotide regulatory protein Gi‐2 in hepatocytes and prevented the action of insulin in reducing the level of phosphorylation of this G‐protein.

U2 - 10.1002/jcb.240550008

DO - 10.1002/jcb.240550008

M3 - Article

C2 - 7929619

AN - SCOPUS:0028243842

VL - 55

SP - 66

EP - 82

JO - Journal of Cellular Biochemistry

JF - Journal of Cellular Biochemistry

SN - 0730-2312

IS - S1994A

ER -