B6N.129S6(B6J)-Chrm3^tm1Jwe/J

Stock number: 030163
Product name: M3R- , M3- , mAChR3- , M3 muscarinic receptor single KO
Research areas: Cell Biology Research, Neurobiology Research, Research Tools

Description

M3R-/- mice have a muscarinic acetylcholine receptor (mAChR) knock-out allele, and may be useful for studying neurotransmission, regulation of food intake, smooth-muscle contractility (airway, GI, bladder, etc.) and glandular secretion (salivary, exocrine pancreas, endocrine pancreatic insulin, etc.).
Dr. Jürgen Wess has five C57BL/6N-congenic mAChR knock-out strains available from The Jackson Laboratory: M1R-/- (Stock No. 030161), M2R-/- (Stock No. 030162), M3R-/- (Stock No. 030163), M4R-/- (Stock No. 030164) and M5R-/- (Stock No. 030165).

Detailed description

The muscarinic acetylcholine receptors (mAChRs) are members of the superfamily of G-protein-coupled receptors (GPCRs). The five molecularly distinct mammalian mAChR subtypes (M1-M5) are expressed in many regions of the CNS (in both neurons and glial cells) and in virtually all peripheral tissues.
The odd-numbered mAChR subtypes (M1, M3, M5) preferentially couple to G_q/11 proteins resulting in the activation of phospholipase C - which in turn leads to inositol trisphosphate-mediated intracellular calcium release and diacylglycerol-mediated protein kinase C activation.
In contrast, the M2 and M4 mAChR subtypes selectively couple to G_i/o proteins, resulting in the inhibition of adenylyl cyclase and voltage-activated calcium channels, as well as other cellular responses.
All five muscarinic receptor subtypes are expressed in the CNS (each subtype shows a distinct expression pattern). In peripheral tissues, most muscarinic actions of acetylcholine are mediated by M2 and M3 receptors.
Mice singly-deficient in the M1-M5 mAChRs are viable, fertile and generally healthy. However, each strain displays distinct alterations in pharmacological, behavioral, biochemical, neurochemical and/or electrophysiological responses.

Dr. Jürgen Wess has five C57BL/6N-congenic mAChR knock-out strains available from The Jackson Laboratory: M1R-/- (Stock No. 030161), M2R-/- (Stock No. 030162), M3R-/- (Stock No. 030163 ; described below), M4R-/- (Stock No. 030164) and M5R-/- (Stock No. 030165).

Stock No. 030163: The M3 muscarinic receptor knockout allele has a PGK-neo cassette disrupting the Chrm3 locus. No functional M3 receptor expression is detected from the knockout allele. Homozygous mice (M3R-/-, M3-/-, mAChR3-/-) have no compensatory changes in expression level of the other four mAChRs (M1, M2, M4, M5). M3R-/- mice are viable, fertile and generally healthy - with the considerations below.
Homozygotes (on C57BL/6J;129) are hypophagic and lean - exhibiting decreased food intake, body weight and peripheral fat deposits, and low serum leptin and serum insulin levels [PMID:11242080].
M3R-/- mice (N10 on C57BL/6NTac) exhibit increased metabolic rate, locomotor activity, body temperature and sympathetic tone [PMID:17084710].
The donating investigator suggests that when mating homozygous females with homozygous males, delaying wean until postnatal week four decreases the incidence of post-wean mortality. To date (February 2017), they observe no phenotype changes between these C57BL/6N-congenic M3R-/- mice and the same knock-out maintained on other genetic backgrounds (such as mixed CF1;129 or mixed C57BL6J ;129).

As of April 2018, The Jackson Laboratory Repository live colony exhibits little-to-no productivity when maintained by breeding homozygous mice together. Therefore, when maintaining our live colony, heterozygous mice may be bred together, to wildtype mice from the colony or to C57BL/6NJ inbred mice (Stock No. 005304). In addition, we breed heterozygous females to homozygous males.

In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. It should be noted that the phenotype of Stock No. 030163 (C57BL/6N-congenic M3R-) could vary from that originally described on different backgrounds (e.g., CF1;129 or C57BL/6;129). We may modify the strain description if necessary as published results become available.

Development

The M3 muscarinic receptor knockout allele (M3R-, M3-, mAChR3-) was created in the laboratory of Dr. Jürgen Wess (NIH-NIDDK). A targeting vector was designed to replace a 1.6 kbp genomic fragment (including the translation start site) of the cholinergic receptor, muscarinic 3 locus (Chrm3) on chromosome 13 with a PGK-neomycin resistance cassette. The construct was electroporated into 129S6/SvEvTac-derived TC-1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric males were bred with C57BL/6J females for germline transmission. The M3R- colony was backcrossed with C57BL/6NTac wildtype mice for at least ten generations prior to sending males with black coat color to The Jackson Laboratory Repository in 2017. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6NJ oocytes (Stock No. 005304).
Of note, it is not known if the Y chromosome has been fixed to the C57BL/6J background during backcrossing.

Allele

Symbol: Chrm3^tm1Jwe
Name: targeted mutation 1, Jurgen Wess
MGI accession ID: MGI:2155562
Generation method: Targeted
Attributes: Null/Knockout
Synonyms: M3-; M3R-; mAChR3^-
Marker symbol: Chrm3
Marker name: cholinergic receptor, muscarinic 3, cardiac
Marker synonyms: Chrm-3; EGBRS; HM3; m3AChR; M3R; muscarinic acetylcholine receptor 3; PBS
Chromosome: 13
Strain of origin: 129S6/SvEvTac
Molecular note: A 1.6 kb genomic fragment including the translation start site was replaced with a neomycin resistance cassette.