Novel inhibition of gbetagamma-activated potassium currents induced
by M(2) muscarinic receptors via a pertussis toxin-insensitive pathway
M. Bunemann, T. Meyer, L. Pott, and M. Hosey. J Biol Chem, 275 (17):
12537-45(April 2000)Bunemann, M Meyer, T Pott, L Hosey, M HL 50121/HL/NHLBI NIH HHS/United
States Research Support, Non-U.S. Gov't Research Support, U.S. Gov't,
P.H.S. United states The Journal of biological chemistry J Biol Chem.
2000 Apr 28;275(17):12537-45..
Abstract
G(i) protein-coupled receptors such as the M(2) muscarinic acetylcholine
receptor (mAChR) and A(1) adenosine receptor have been shown to activate
G protein-activated inwardly rectifying K(+) channels (GIRKs) via
pertussis toxin-sensitive G proteins in atrial myocytes and in many
neuronal cells. Here we show that muscarinic M(2) receptors not only
activate but also reversibly inhibit these K(+) currents when stimulated
with agonist for up to 2 min. The M(2) mAChR-mediated inhibition
of the channel was also observed when the channels were first activated
by inclusion of guanosine 5'-O-(thiotriphosphate) in the pipette.
Under these conditions the M(2) mAChR-induced inhibition was quasi-irreversible,
suggesting a role for G proteins in the inhibitory process. In contrast,
when GIRK currents were maximally activated by co-expressing exogenous
Gbetagamma, the extent of acetylcholine (ACh)-induced inhibition
was significantly reduced, suggesting competition between the receptor-mediated
inhibition and the large pool of available Gbetagamma subunits. The
signaling pathway that led to the ACh-induced inhibition of GIRK
channels was unaffected by pertussis toxin pretreatment. Furthermore,
the internalization and agonist-induced phosphorylation of M(2) mAChR
was not required because a phosphorylation- and internalization-deficient
mutant of the M(2) mAChR was as potent as the wild-type counterpart.
Pharmacological agents modulating various protein kinases or phosphatidylinositol
3-kinase did not affect the inhibition of GIRK currents. Furthermore,
the signaling pathway that mediates GIRK current inhibition was found
to be membrane-delimited because bath application of ACh did not
inhibit GIRK channel activity in cell-attached patches. Other G protein-coupled
receptors including M(4) mAChR and alpha(1A) adrenergic receptors
also caused the inhibition, whereas other G protein-coupled receptors
including A(1) and A(3) adenosine receptors and alpha(2A) and alpha(2C)
adrenergic receptors could not induce the inhibition. The presented
results suggest the existence of a novel signaling pathway that can
be activated selectively by M(2) and M(4) mAChR but not by adenosine
receptors and that involves non-pertussis toxin-sensitive G proteins
leading to an inhibition of Gbetagamma-activated GIRK currents in
a membrane-delimited fashion.
Bunemann, M Meyer, T Pott, L Hosey, M HL 50121/HL/NHLBI NIH HHS/United
States Research Support, Non-U.S. Gov't Research Support, U.S. Gov't,
P.H.S. United states The Journal of biological chemistry J Biol Chem.
2000 Apr 28;275(17):12537-45.
%0 Journal Article
%1 Bunemann2000
%A Bunemann, M.
%A Meyer, T.
%A Pott, L.
%A Hosey, M.
%D 2000
%J J Biol Chem
%K & *Pertussis *Potassium Animals Bordetella/*metabolism CHO Cell Channels Channels, Channels/metabolism Cholinergic/metabolism Cricetinae Factors, G GTP-Binding Humans Inwardly Inwardly-Rectifying Muscarinic/*metabolism P1/metabolism Patch-Clamp Potassium Potassium/*metabolism Protein-Coupled Proteins/metabolism Purinergic Rectifying Surface/*antagonists Techniques Toxin Transfection Virulence inhibitors Receptor
%N 17
%P 12537-45
%T Novel inhibition of gbetagamma-activated potassium currents induced
by M(2) muscarinic receptors via a pertussis toxin-insensitive pathway
%U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10777542
%V 275
%X G(i) protein-coupled receptors such as the M(2) muscarinic acetylcholine
receptor (mAChR) and A(1) adenosine receptor have been shown to activate
G protein-activated inwardly rectifying K(+) channels (GIRKs) via
pertussis toxin-sensitive G proteins in atrial myocytes and in many
neuronal cells. Here we show that muscarinic M(2) receptors not only
activate but also reversibly inhibit these K(+) currents when stimulated
with agonist for up to 2 min. The M(2) mAChR-mediated inhibition
of the channel was also observed when the channels were first activated
by inclusion of guanosine 5'-O-(thiotriphosphate) in the pipette.
Under these conditions the M(2) mAChR-induced inhibition was quasi-irreversible,
suggesting a role for G proteins in the inhibitory process. In contrast,
when GIRK currents were maximally activated by co-expressing exogenous
Gbetagamma, the extent of acetylcholine (ACh)-induced inhibition
was significantly reduced, suggesting competition between the receptor-mediated
inhibition and the large pool of available Gbetagamma subunits. The
signaling pathway that led to the ACh-induced inhibition of GIRK
channels was unaffected by pertussis toxin pretreatment. Furthermore,
the internalization and agonist-induced phosphorylation of M(2) mAChR
was not required because a phosphorylation- and internalization-deficient
mutant of the M(2) mAChR was as potent as the wild-type counterpart.
Pharmacological agents modulating various protein kinases or phosphatidylinositol
3-kinase did not affect the inhibition of GIRK currents. Furthermore,
the signaling pathway that mediates GIRK current inhibition was found
to be membrane-delimited because bath application of ACh did not
inhibit GIRK channel activity in cell-attached patches. Other G protein-coupled
receptors including M(4) mAChR and alpha(1A) adrenergic receptors
also caused the inhibition, whereas other G protein-coupled receptors
including A(1) and A(3) adenosine receptors and alpha(2A) and alpha(2C)
adrenergic receptors could not induce the inhibition. The presented
results suggest the existence of a novel signaling pathway that can
be activated selectively by M(2) and M(4) mAChR but not by adenosine
receptors and that involves non-pertussis toxin-sensitive G proteins
leading to an inhibition of Gbetagamma-activated GIRK currents in
a membrane-delimited fashion.
@article{Bunemann2000,
abstract = {G(i) protein-coupled receptors such as the M(2) muscarinic acetylcholine
receptor (mAChR) and A(1) adenosine receptor have been shown to activate
G protein-activated inwardly rectifying K(+) channels (GIRKs) via
pertussis toxin-sensitive G proteins in atrial myocytes and in many
neuronal cells. Here we show that muscarinic M(2) receptors not only
activate but also reversibly inhibit these K(+) currents when stimulated
with agonist for up to 2 min. The M(2) mAChR-mediated inhibition
of the channel was also observed when the channels were first activated
by inclusion of guanosine 5'-O-(thiotriphosphate) in the pipette.
Under these conditions the M(2) mAChR-induced inhibition was quasi-irreversible,
suggesting a role for G proteins in the inhibitory process. In contrast,
when GIRK currents were maximally activated by co-expressing exogenous
Gbetagamma, the extent of acetylcholine (ACh)-induced inhibition
was significantly reduced, suggesting competition between the receptor-mediated
inhibition and the large pool of available Gbetagamma subunits. The
signaling pathway that led to the ACh-induced inhibition of GIRK
channels was unaffected by pertussis toxin pretreatment. Furthermore,
the internalization and agonist-induced phosphorylation of M(2) mAChR
was not required because a phosphorylation- and internalization-deficient
mutant of the M(2) mAChR was as potent as the wild-type counterpart.
Pharmacological agents modulating various protein kinases or phosphatidylinositol
3-kinase did not affect the inhibition of GIRK currents. Furthermore,
the signaling pathway that mediates GIRK current inhibition was found
to be membrane-delimited because bath application of ACh did not
inhibit GIRK channel activity in cell-attached patches. Other G protein-coupled
receptors including M(4) mAChR and alpha(1A) adrenergic receptors
also caused the inhibition, whereas other G protein-coupled receptors
including A(1) and A(3) adenosine receptors and alpha(2A) and alpha(2C)
adrenergic receptors could not induce the inhibition. The presented
results suggest the existence of a novel signaling pathway that can
be activated selectively by M(2) and M(4) mAChR but not by adenosine
receptors and that involves non-pertussis toxin-sensitive G proteins
leading to an inhibition of Gbetagamma-activated GIRK currents in
a membrane-delimited fashion.},
added-at = {2010-12-14T18:12:02.000+0100},
author = {Bunemann, M. and Meyer, T. and Pott, L. and Hosey, M.},
biburl = {https://www.bibsonomy.org/bibtex/2c38524d6d668560499468a9f85202585/pharmawuerz},
endnotereftype = {Journal Article},
interhash = {980477a8f0fab2ab4fae658ec3589242},
intrahash = {c38524d6d668560499468a9f85202585},
issn = {0021-9258 (Print) 0021-9258 (Linking)},
journal = {J Biol Chem},
keywords = {& *Pertussis *Potassium Animals Bordetella/*metabolism CHO Cell Channels Channels, Channels/metabolism Cholinergic/metabolism Cricetinae Factors, G GTP-Binding Humans Inwardly Inwardly-Rectifying Muscarinic/*metabolism P1/metabolism Patch-Clamp Potassium Potassium/*metabolism Protein-Coupled Proteins/metabolism Purinergic Rectifying Surface/*antagonists Techniques Toxin Transfection Virulence inhibitors Receptor},
month = {Apr 28},
note = {Bunemann, M Meyer, T Pott, L Hosey, M HL 50121/HL/NHLBI NIH HHS/United
States Research Support, Non-U.S. Gov't Research Support, U.S. Gov't,
P.H.S. United states The Journal of biological chemistry J Biol Chem.
2000 Apr 28;275(17):12537-45.},
number = 17,
pages = {12537-45},
shorttitle = {Novel inhibition of gbetagamma-activated potassium currents induced
by M(2) muscarinic receptors via a pertussis toxin-insensitive pathway},
timestamp = {2010-12-14T18:20:38.000+0100},
title = {Novel inhibition of gbetagamma-activated potassium currents induced
by M(2) muscarinic receptors via a pertussis toxin-insensitive pathway},
url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10777542},
volume = 275,
year = 2000
}