The voltage-sensitive cardiac M2 muscarinic receptor modulates the inward rectification of the G protein-coupled, ACh-gated K+ current

2018 ◽  
Vol 470 (12) ◽  
pp. 1765-1776 ◽  
Author(s):  
Pedro D. Salazar-Fajardo ◽  
Iván A. Aréchiga-Figueroa ◽  
Ana Laura López-Serrano ◽  
Julio C. Rodriguez-Elias ◽  
Javier Alamilla ◽  
...  
Keyword(s):  
G Protein ◽  
Muscarinic Receptor ◽  
Inward Rectification ◽  
M2 Muscarinic Receptor ◽  
K Current ◽  
G Protein Coupled

Role of internalization of M2 muscarinic receptor via clathrin-coated vesicles in desensitization of the muscarinic K+ current in heart

2007 ◽  
Vol 292 (4) ◽  
pp. H1737-H1746 ◽  
Author(s):  
T. T. Yamanushi ◽  
Z. Shui ◽  
R. N. Leach ◽  
H. Dobrzynski ◽  
T. W. Claydon ◽  
...  
Keyword(s):  
G Protein ◽  
Muscarinic Receptor ◽  
Coated Vesicles ◽  
Receptor Internalization ◽  
Muscarinic Agonist ◽  
Receptor Kinase ◽  
Time Constants ◽  
Protein Receptor ◽  
M2 Muscarinic Receptor ◽  
K Current

In the heart, ACh activates the ACh-activated K+ current ( IK,ACh) via the M2 muscarinic receptor. The relationship between desensitization of IK,ACh and internalization of the M2 receptor has been studied in rat atrial cells. On application of the stable muscarinic agonist carbachol for 2 h, IK,ACh declined by ∼62% with time constants of 1.5 and 26.9 min, whereas ∼83% of the M2 receptor was internalized from the cell membrane with time constants of 2.9 and 51.6 min. Transfection of the cells with β-adrenergic receptor kinase 1 (G protein-receptor kinase 2) and β-arrestin 2 significantly increased IK,ACh desensitization and M2 receptor internalization during a 3-min application of agonist. Internalized M2 receptor in cells exposed to carbachol for 2 h was colocalized with clathrin and not caveolin. It is concluded that a G protein-receptor kinase 2- and β-arrestin 2-dependent internalization of the M2 receptor into clathrin-coated vesicles could play a major role in IK,ACh desensitization.

scholarly journals Inhibition of G protein-coupled receptor trafficking in neuroblastoma cells by MAP 4 decoration of microtubules

2002 ◽  
Vol 283 (6) ◽  
pp. H2379-H2388 ◽  
Author(s):  
Guangmao Cheng ◽  
Yoshihiro Iijima ◽  
Yuji Ishibashi ◽  
Dhandapani Kuppuswamy ◽  
George Cooper
Keyword(s):  
G Protein ◽  
Muscarinic Receptor ◽  
Receptor Binding ◽  
Neuroblastoma Cells ◽  
Pressure Overload ◽  
G Protein Coupled Receptors ◽  
Structural Protein ◽  
Microtubule Network ◽  
Intact Cells ◽  
G Protein Coupled

One mechanism for the reappearance of G protein-coupled receptors after agonist activation is microtubule-based transport. In pressure-overload cardiac hypertrophy, there is downregulation of G protein-coupled receptors and the appearance of a densified microtubule network extensively decorated by a microtubule-associated protein, MAP 4. Our hypothesis is that overdecoration of a dense microtubule network with this structural protein, as in hypertrophied myocardium, would impede receptor recovery. We tested this hypothesis by studying muscarinic acetylcholine receptor (mAChR) internalization and recovery after agonist stimulation in neuroblastoma cells. Exposure of cells to carbachol, a muscarinic receptor agonist, decreased membrane receptor binding activity. After carbachol withdrawal, receptor binding recovered toward the initial value. When microtubules were depolymerized before carbachol withdrawal, mAChR recovery was only 44% of that in intact cells. Cells were then infected with an adenovirus containing MAP 4 cDNA. MAP 4 protein decorated the microtubules extensively, and receptor recovery upon carbachol withdrawal was reduced to 54% of control. Thus muscarinic receptor recovery after agonist exposure is microtubule dependent, and MAP 4 decoration of microtubules inhibits receptor recovery.

Acetylcholine activates a glibenclamide-sensitive K+ current in cat atrial myocytes

1995 ◽  
Vol 268 (3) ◽  
pp. H1322-H1334 ◽  
Author(s):  
Y. G. Wang ◽  
S. L. Lipsius
Keyword(s):  
Muscarinic Receptor ◽  
Preceding Paper ◽  
Kinase C ◽  
M2 Muscarinic Receptor ◽  
Cell Recording ◽  
K Current ◽  
Receptor Block ◽  
Atrial Myocyte ◽  
M1 Muscarinic ◽  
K Currents

The preceding paper [Y. G. Wang and S. L. Lipsius, Am. J. Physiol. 268 (Heart Circ. Physiol. 37): H1313–H1321, 1995.] showed that when an atrial myocyte is treated with two consecutive exposures to acetylcholine (ACh) separated by a recovery interval, the second ACh exposure elicits a larger increase in K+ conductance than the first ACh exposure. In the present study a nystatin-perforated patch whole cell recording method was used to determine the mechanisms underlying the potentiating effect of ACh on ACh-induced K+ currents and the nature of the potentiated K+ current. The K+ current potentiated by the second ACh exposure was selectively abolished by 1) M1 muscarinic receptor block by 0.1 microM pirenzepine, 2) depletion of sarcoplasmic reticulum (SR) Ca2+ stores by 1 microM ryanodine or 10 mM caffeine, 3) intracellular dialysis with 10 mM ethylene glycolbis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), 4) omitting external Ca2+, 5) 50% external Na+, 6) inhibition of protein kinase C by 0.01 microM staurosporine or 0.1 microM calphostin C, or 7) inhibition of ATP-sensitive K+ channels with 10 microM glibenclamide (Glib). AFDX-116 (100 microM), an M2 muscarinic receptor antagonist, selectively abolished the conventional ACh-activated K+ current and revealed an ACh-activated Glib-sensitive K+ current. In addition, with K+ conductances blocked and zero external Ca2+, 10 microM ACh induced a small nonselective inward current carried by Na+.(ABSTRACT TRUNCATED AT 250 WORDS)

G protein-coupled receptor kinase 5 regulates airway responses induced by muscarinic receptor activation

2004 ◽  
Vol 286 (2) ◽  
pp. L312-L319 ◽  
Author(s):  
J. K. L. Walker ◽  
R. R. Gainetdinov ◽  
D. S. Feldman ◽  
P. K. McFawn ◽  
M. G. Caron ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
G Protein ◽  
Muscarinic Receptor ◽  
Airway Smooth Muscle ◽  
Muscarinic Receptors ◽  
Muscle Relaxation ◽  
Receptor Activation ◽  
Smooth Muscle Relaxation ◽  
Airway Responses ◽  
G Protein Coupled

G protein-coupled receptors (GPCRs) transduce extracellular signals into intracellular events. The waning responsiveness of GPCRs in the face of persistent agonist stimulation, or desensitization, is a necessary event that ensures physiological homeostasis. GPCR kinases (GRKs) are important regulators of GPCR desensitization. GRK5, one member of the GRK family, desensitizes central M2 muscarinic receptors in mice. We questioned whether GRK5 might also be an important regulator of peripheral muscarinic receptor responsiveness in the cardiopulmonary system. Specifically, we wanted to determine the role of GRK5 in regulating muscarinic receptor-mediated control of airway smooth muscle tone or regulation of cholinergic-induced bradycardia. Tracheal pressure, heart rate, and tracheal smooth muscle tension were measured in mice having a targeted deletion of the GRK5 gene ( GRK5- /-) and littermate wild-type (WT) control mice. Both in vivo and in vitro results showed that the airway contractile response to a muscarinic receptor agonist was not different between GRK5- /- and WT mice. However, the relaxation component of bilateral vagal stimulation and the airway smooth muscle relaxation resulting from β2-adrenergic receptor activation were diminished in GRK5- /- mice. These data suggest that M2 muscarinic receptor-mediated opposition of airway smooth muscle relaxation is regulated by GRK5 and is, therefore, excessive in GRK5- /- mice. In addition, this study shows that GRK5 regulates pulmonary responses in a tissue- and receptor-specific manner but does not regulate peripheral cardiac muscarinic receptors. GRK5 regulation of airway responses may have implications in obstructive airway diseases such as asthma or chronic obstructive pulmonary disease.

scholarly journals The coupling of the M2 muscarinic receptor to its G protein is voltage dependent

PLoS ONE ◽  
2019 ◽  
Vol 14 (10) ◽  
pp. e0224367
Author(s):  
Yair Ben-Chaim ◽  
Chava Broide ◽  
Hanna Parnas
Keyword(s):  
G Protein ◽  
Muscarinic Receptor ◽  
M2 Muscarinic Receptor ◽  
Voltage Dependent

scholarly journals Allosteric modulation in monomers and oligomers of a G protein-coupled receptor

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Rabindra V Shivnaraine ◽  
Brendan Kelly ◽  
Krishana S Sankar ◽  
Dar'ya S Redka ◽  
Yi Rang Han ◽  
...  
Keyword(s):  
Muscarinic Receptor ◽  
Allosteric Modulation ◽  
Atomic Level ◽  
Allosteric Site ◽  
Allosteric Interactions ◽  
M2 Muscarinic Receptor ◽  
Orthosteric Ligands ◽  
Dynamics Simulations ◽  
G Protein Coupled ◽  
Allosteric Properties

The M2 muscarinic receptor is the prototypic model of allostery in GPCRs, yet the molecular and the supramolecular determinants of such effects are unknown. Monomers and oligomers of the M2 muscarinic receptor therefore have been compared to identify those allosteric properties that are gained in oligomers. Allosteric interactions were monitored by means of a FRET-based sensor of conformation at the allosteric site and in pharmacological assays involving mutants engineered to preclude intramolecular effects. Electrostatic, steric, and conformational determinants of allostery at the atomic level were examined in molecular dynamics simulations. Allosteric effects in monomers were exclusively negative and derived primarily from intramolecular electrostatic repulsion between the allosteric and orthosteric ligands. Allosteric effects in oligomers could be positive or negative, depending upon the allosteric-orthosteric pair, and they arose from interactions within and between the constituent protomers. The complex behavior of oligomers is characteristic of muscarinic receptors in myocardial preparations.

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