Muscarinic acetylcholine receptor M2

The muscarinic acetylcholine receptor M₂, also known as the cholinergic receptor, muscarinic 2, is a muscarinic acetylcholine receptor that in humans is encoded by the CHRM2 gene.^[5] Multiple alternatively spliced transcript variants have been described for this gene.^[5] It is G_i-coupled, reducing intracellular levels of cAMP.

CHRM2
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 3UON, 4MQS, 4MQT
Identifiers
Aliases	CHRM2, HM2, cholinergic receptor muscarinic 2
External IDs	OMIM: 118493; MGI: 88397; HomoloGene: 20190; GeneCards: CHRM2; OMA:CHRM2 - orthologs
Gene location (Human) Chr. Chromosome 7 (human)[1] Band 7q33 Start 136,868,652 bp[1] End 137,020,255 bp[1]
Gene location (Mouse) Chr. Chromosome 6 (mouse)[2] Band 6|6 B1 Start 36,365,019 bp[2] End 36,505,349 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in stromal cell of endometrium right auricle apex of heart muscle layer of sigmoid colon left ventricle gallbladder testicle epithelium of colon right lung smooth muscle tissue Top expressed in interventricular septum left ventricle upper lip olfactory bulb brain stem stomach lower lip duodenum pons medulla oblongata More reference expression data BioGPS n/a
Gene ontology Molecular function G protein-coupled receptor activity signal transducer activity G protein-coupled acetylcholine receptor activity arrestin family protein binding G protein-coupled serotonin receptor activity neurotransmitter receptor activity Cellular component axon terminus postsynaptic membrane membrane plasma membrane synapse integral component of plasma membrane cell junction soma dendrite symmetric synapse asymmetric synapse clathrin-coated vesicle membrane integral component of membrane glutamatergic synapse cholinergic synapse integral component of postsynaptic membrane integral component of presynaptic membrane Biological process G protein-coupled acetylcholine receptor signaling pathway G protein-coupled receptor signaling pathway regulation of smooth muscle contraction adenylate cyclase-modulating G protein-coupled receptor signaling pathway G protein-coupled receptor signaling pathway, coupled to cyclic nucleotide second messenger response to virus synaptic transmission, cholinergic nervous system development adenylate cyclase-inhibiting G protein-coupled acetylcholine receptor signaling pathway phospholipase C-activating G protein-coupled acetylcholine receptor signaling pathway signal transduction membrane organization regulation of heart contraction regulation of synaptic vesicle exocytosis chemical synaptic transmission G protein-coupled serotonin receptor signaling pathway Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 1129 243764 Ensembl ENSG00000181072 ENSMUSG00000045613 UniProt P08172 Q9ERZ4 RefSeq (mRNA) NM_000739 NM_001006626 NM_001006627 NM_001006628 NM_001006629 NM_001006630 NM_001006631 NM_001006632 NM_001006633 NM_001378972 NM_001378973 NM_203491 RefSeq (protein) NP_000730 NP_001006627 NP_001006628 NP_001006629 NP_001006630 NP_001006631 NP_001006632 NP_001006633 NP_001365901 NP_001365902 NP_987076 Location (UCSC) Chr 7: 136.87 – 137.02 Mb Chr 6: 36.37 – 36.51 Mb PubMed search [3] [4]
Wikidata
View/Edit Human View/Edit Mouse

Function

Heart

The M₂ muscarinic receptors are located in the heart, where they act to slow the heart rate down to normal sinus rhythm after negative stimulatory actions of the parasympathetic nervous system, by slowing the speed of depolarization. They also reduce contractile forces of the atrial cardiac muscle, and reduce conduction velocity of the atrioventricular node (AV node). However, they have little effect on the contractile forces of the ventricular muscle, slightly decreasing force.

Airway smooth muscle

Both M₂ and M₃ muscarinic receptors are expressed in the smooth muscles of the airway, with the majority of the receptors being the M₂ type. Activation of the M₂ receptors, which are coupled to G_i, inhibits the β-adrenergic mediated relaxation of the airway smooth muscle. Synergistically, activation of the M₃ receptors, which couple to G_q, stimulates contraction of the airway smooth muscle.^[6]

IQ

A Dutch family study found that there is "a highly significant association" between the CHRM2 gene and intelligence as measured by the Wechsler Adult Intelligence Scale-Revised.^[7] A similar association was found independently in the Minnesota Twin and Family Study.^[8][9]

However, a larger 2009 study attempting to replicate this claim instead found no significant association between the CHRM2 gene and intelligence.^[10]

Olfactory behavior

Mediating olfactory guided behaviors (e.g. odor discrimination, aggression, mating).^[11]

Mechanism of action

M₂ muscarinic receptors act via a G_i type receptor, which causes a decrease in cAMP in the cell, generally leading to inhibitory-type effects. They appear to generally serve as autoreceptors.^[12]

In addition, they modulate G protein-coupled inwardly-rectifying potassium channels.^[13][14] In the heart, this contributes to a decreased heart rate. They do so by the G_βγ subunit of the G protein; G_βγ shifts the open probability of K⁺ channels in the membrane of the cardiac pacemaker cells, which causes an outward current of potassium, effectively hyperpolarizing the membrane, which slows down the heart rate.

Ligands

Few highly selective M₂ agonists are available at present, although there are several non-selective muscarinic agonists that stimulate M₂, and a number of selective M₂ antagonists are available.

Agonists

• (2S,2'R,3'S,5'R)-1-methyl-2-(2-methyl-1,3-oxathiolan-5-yl)pyrrolidine 3-sulfoxide methyl iodide (selective for M₂ but only partial agonist)^[15]
• Berberine
• Iper-8-Naph (alias N-8-Iper, bitopic/dualsteric agonist)^[16][17][18]
• Methacholine
• PAI (photoswitchable agonist)^[19]

Antagonists

• AFDX-384
• Atropine^[13]
• Chlorpromazine
• Dicycloverine^[13]
• Dimenhydrinate
• Dimethindene
• Diphenhydramine
• Gallamine
• Hyoscyamine^[20]
• Ipratropium^[13]
• Methoctramine^[21]
• Otenzepad
• Oxybutynin^[13]
• Thorazine
• Tolterodine^[13]
• Trimipramine

See also

• Muscarinic acetylcholine receptor

References

1. GRCh38: Ensembl release 89: ENSG00000181072 – Ensembl, May 2017
2. GRCm38: Ensembl release 89: ENSMUSG00000045613 – Ensembl, May 2017
3. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
4. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
5. "Entrez Gene: CHRM2 cholinergic receptor, muscarinic 2".
6. Hirshman CA, Lande B, Croxton TL (January 1999). "Role of M2 muscarinic receptors in airway smooth muscle contraction". Life Sciences. 64 (6–7): 443–448. doi:10.1016/S0024-3205(98)00586-4. PMID 10069508.
7. Gosso MF, van Belzen M, de Geus EJ, Polderman JC, Heutink P, Boomsma DI, Posthuma D (November 2006). "Association between the CHRM2 gene and intelligence in a sample of 304 Dutch families". Genes, Brain and Behavior. 5 (8): 577–584. doi:10.1111/j.1601-183X.2006.00211.x. PMID 17081262.
8. Comings DE, Wu S, Rostamkhani M, McGue M, Lacono WG, Cheng LS, MacMurray JP (January 2003). "Role of the cholinergic muscarinic 2 receptor (CHRM2) gene in cognition". Molecular Psychiatry. 8 (1): 10–11. doi:10.1038/sj.mp.4001095. PMID 12556901. S2CID 22314941.
9. Dick DM, Aliev F, Kramer J, Wang JC, Hinrichs A, Bertelsen S, et al. (March 2007). "Association of CHRM2 with IQ: converging evidence for a gene influencing intelligence". Behavior Genetics. 37 (2): 265–272. doi:10.1007/s10519-006-9131-2. PMID 17160701. S2CID 9353852.
10. Lind PA, Luciano M, Horan MA, Marioni RE, Wright MJ, Bates TC, et al. (September 2009). "No association between Cholinergic Muscarinic Receptor 2 (CHRM2) genetic variation and cognitive abilities in three independent samples". Behavior Genetics. 39 (5): 513–523. doi:10.1007/s10519-009-9274-z. PMID 19418213. S2CID 2523697.
11. Smith RS, Hu R, DeSouza A, Eberly CL, Krahe K, Chan W, Araneda RC (July 2015). "Differential Muscarinic Modulation in the Olfactory Bulb". The Journal of Neuroscience. 35 (30): 10773–10785. doi:10.1523/JNEUROSCI.0099-15.2015. PMC 4518052. PMID 26224860.
12. Douglas CL, Baghdoyan HA, Lydic R (December 2001). "M2 muscarinic autoreceptors modulate acetylcholine release in prefrontal cortex of C57BL/6J mouse". The Journal of Pharmacology and Experimental Therapeutics. 299 (3): 960–966. PMID 11714883.
13. Rang HP (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4.
14. Boron WF, Boulpaep EL (2005). Medical Physiology. Philadelphia: Elsevier Saunders. p. 387. ISBN 1-4160-2328-3.
15. Scapecchi S, Matucci R, Bellucci C, Buccioni M, Dei S, Guandalini L, et al. (March 2006). "Highly chiral muscarinic ligands: the discovery of (2S,2'R,3'S,5'R)-1-methyl-2-(2-methyl-1,3-oxathiolan-5-yl)pyrrolidine 3-sulfoxide methyl iodide, a potent, functionally selective, M2 partial agonist". Journal of Medicinal Chemistry. 49 (6): 1925–1931. doi:10.1021/jm0510878. PMID 16539379.
16. Matera C, Flammini L, Quadri M, Vivo V, Ballabeni V, Holzgrabe U, et al. (March 2014). "Bis(ammonio)alkane-type agonists of muscarinic acetylcholine receptors: synthesis, in vitro functional characterization, and in vivo evaluation of their analgesic activity". European Journal of Medicinal Chemistry. 75: 222–232. doi:10.1016/j.ejmech.2014.01.032. PMID 24534538.
17. Cristofaro I, Spinello Z, Matera C, Fiore M, Conti L, De Amici M, et al. (September 2018). "Activation of M2 muscarinic acetylcholine receptors by a hybrid agonist enhances cytotoxic effects in GB7 glioblastoma cancer stem cells". Neurochemistry International. 118: 52–60. doi:10.1016/j.neuint.2018.04.010. PMID 29702145. S2CID 207125517.
18. Bock A, Merten N, Schrage R, Dallanoce C, Bätz J, Klöckner J, et al. (2012-09-04). "The allosteric vestibule of a seven transmembrane helical receptor controls G-protein coupling". Nature Communications. 3: 1044. Bibcode:2012NatCo...3.1044B. doi:10.1038/ncomms2028. PMC 3658004. PMID 22948826.
19. Riefolo F, Matera C, Garrido-Charles A, Gomila AM, Sortino R, Agnetta L, et al. (May 2019). "Optical Control of Cardiac Function with a Photoswitchable Muscarinic Agonist". Journal of the American Chemical Society. 141 (18): 7628–7636. doi:10.1021/jacs.9b03505. hdl:2445/147236. PMID 31010281. S2CID 128361100.
20. Edwards Pharmaceuticals, Inc., Belcher Pharmaceuticals, Inc. (May 2010), "ED-SPAZ- hyoscyamine sulfate tablet, orally disintegrating", DailyMed, U.S. National Library of Medicine, retrieved January 13, 2013
21. Melchiorre C, Angeli P, Lambrecht G, Mutschler E, Picchio MT, Wess J (December 1987). "Antimuscarinic action of methoctramine, a new cardioselective M-2 muscarinic receptor antagonist, alone and in combination with atropine and gallamine". European Journal of Pharmacology. 144 (2): 117–124. doi:10.1016/0014-2999(87)90509-7. PMID 3436364.

Further reading

• Goyal RK (October 1989). "Muscarinic receptor subtypes. Physiology and clinical implications". The New England Journal of Medicine. 321 (15): 1022–1029. doi:10.1056/NEJM198910123211506. PMID 2674717.
• Brann MR, Ellis J, Jørgensen H, Hill-Eubanks D, Jones SV (1993). "Chapter 12: Muscarinic acetylcholine receptor subtypes: Localization and structure/Function". Cholinergic Function and Dysfunction. Progress in Brain Research. Vol. 98. pp. 121–7. doi:10.1016/S0079-6123(08)62388-2. ISBN 9780444897176. PMID 8248499.
• van Koppen CJ, Nathanson NM (December 1990). "Site-directed mutagenesis of the m2 muscarinic acetylcholine receptor. Analysis of the role of N-glycosylation in receptor expression and function". The Journal of Biological Chemistry. 265 (34): 20887–20892. doi:10.1016/S0021-9258(17)45299-9. PMID 2249995.
• Ashkenazi A, Ramachandran J, Capon DJ (July 1989). "Acetylcholine analogue stimulates DNA synthesis in brain-derived cells via specific muscarinic receptor subtypes". Nature. 340 (6229): 146–150. Bibcode:1989Natur.340..146A. doi:10.1038/340146a0. PMID 2739737. S2CID 4312544.
• Bonner TI, Buckley NJ, Young AC, Brann MR (July 1987). "Identification of a family of muscarinic acetylcholine receptor genes". Science. 237 (4814): 527–532. Bibcode:1987Sci...237..527B. doi:10.1126/science.3037705. PMID 3037705.
• Peralta EG, Ashkenazi A, Winslow JW, Smith DH, Ramachandran J, Capon DJ (December 1987). "Distinct primary structures, ligand-binding properties and tissue-specific expression of four human muscarinic acetylcholine receptors". The EMBO Journal. 6 (13): 3923–3929. doi:10.1002/j.1460-2075.1987.tb02733.x. PMC 553870. PMID 3443095.
• Badner JA, Yoon SW, Turner G, Bonner TI, Detera-Wadleigh SD (July 1995). "Multipoint genetic linkage analysis of the m2 human muscarinic receptor gene". Mammalian Genome. 6 (7): 489–490. doi:10.1007/BF00360666. PMID 7579899. S2CID 6934445.
• Offermanns S, Simon MI (June 1995). "G alpha 15 and G alpha 16 couple a wide variety of receptors to phospholipase C". The Journal of Biological Chemistry. 270 (25): 15175–15180. doi:10.1074/jbc.270.25.15175. PMID 7797501.
• Russell M, Winitz S, Johnson GL (April 1994). "Acetylcholine muscarinic m1 receptor regulation of cyclic AMP synthesis controls growth factor stimulation of Raf activity". Molecular and Cellular Biology. 14 (4): 2343–2351. doi:10.1128/mcb.14.4.2343. PMC 358601. PMID 8139539.
• Kunapuli P, Onorato JJ, Hosey MM, Benovic JL (January 1994). "Expression, purification, and characterization of the G protein-coupled receptor kinase GRK5". The Journal of Biological Chemistry. 269 (2): 1099–1105. doi:10.1016/S0021-9258(17)42226-5. PMID 8288567.
• Haga K, Kameyama K, Haga T, Kikkawa U, Shiozaki K, Uchiyama H (February 1996). "Phosphorylation of human m1 muscarinic acetylcholine receptors by G protein-coupled receptor kinase 2 and protein kinase C". The Journal of Biological Chemistry. 271 (5): 2776–2782. doi:10.1074/jbc.271.5.2776. PMID 8576254.
• Kostenis E, Conklin BR, Wess J (February 1997). "Molecular basis of receptor/G protein coupling selectivity studied by coexpression of wild type and mutant m2 muscarinic receptors with mutant G alpha(q) subunits". Biochemistry. 36 (6): 1487–1495. doi:10.1021/bi962554d. PMID 9063897.
• Smiley JF, Levey AI, Mesulam MM (June 1998). "Infracortical interstitial cells concurrently expressing m2-muscarinic receptors, acetylcholinesterase and nicotinamide adenine dinucleotide phosphate-diaphorase in the human and monkey cerebral cortex". Neuroscience. 84 (3): 755–769. doi:10.1016/S0306-4522(97)00524-1. PMID 9579781. S2CID 25807845.
• von der Kammer H, Mayhaus M, Albrecht C, Enderich J, Wegner M, Nitsch RM (June 1998). "Muscarinic acetylcholine receptors activate expression of the EGR gene family of transcription factors". The Journal of Biological Chemistry. 273 (23): 14538–14544. doi:10.1074/jbc.273.23.14538. PMID 9603968.
• Sato KZ, Fujii T, Watanabe Y, Yamada S, Ando T, Kazuko F, Kawashima K (April 1999). "Diversity of mRNA expression for muscarinic acetylcholine receptor subtypes and neuronal nicotinic acetylcholine receptor subunits in human mononuclear leukocytes and leukemic cell lines". Neuroscience Letters. 266 (1): 17–20. doi:10.1016/S0304-3940(99)00259-1. PMID 10336173. S2CID 43548155.
• Retondaro FC, Dos Santos Costa PC, Pedrosa RC, Kurtenbach E (November 1999). "Presence of antibodies against the third intracellular loop of the m2 muscarinic receptor in the sera of chronic chagasic patients". FASEB Journal. 13 (14): 2015–2020. doi:10.1096/fasebj.13.14.2015. PMID 10544184. S2CID 38193046.
• Waid DK, Chell M, El-Fakahany EE (July 2000). "M(2) and M(4) muscarinic receptor subtypes couple to activation of endothelial nitric oxide synthase". Pharmacology. 61 (1): 37–42. doi:10.1159/000028378. PMID 10895079. S2CID 43492985.
• Obara K, Arai K, Miyajima N, Hatano A, Tomita Y, Takahashi K (June 2000). "Expression of m2 muscarinic acetylcholine receptor mRNA in primary culture of human prostate stromal cells". Urological Research. 28 (3): 196–200. doi:10.1007/s002400000113. PMID 10929429. S2CID 25697686.
• Matera C, Flammini L, Quadri M, Vivo V, Ballabeni V, Holzgrabe U, et al. (March 2014). "Bis(ammonio)alkane-type agonists of muscarinic acetylcholine receptors: synthesis, in vitro functional characterization, and in vivo evaluation of their analgesic activity". European Journal of Medicinal Chemistry. 75: 222–232. doi:10.1016/j.ejmech.2014.01.032. PMID 24534538.

External links

• "Acetylcholine receptors (muscarinic): M₂". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Archived from the original on 2015-01-02. Retrieved 2008-11-25.
• CHRM2+protein,+human at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
• Overview of all the structural information available in the PDB for UniProt: P08172 (Muscarinic acetylcholine receptor M2) at the PDBe-KB.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.