B6N.129S6(Cg)-Chrm4^tm1Jwe/J

Stock number: 030164
Product name: M4R- , M4- , mAChR4- , M4 muscarinic receptor single KO
Research areas: Cell Biology Research, Neurobiology Research, Research Tools

Description

M4R-/- mice have a muscarinic acetylcholine receptor (mAChR) knock-out allele, and may be useful for studying neurotransmission, as well as the regulation of locomotor activity and dopaminergic signaling.
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), M4R-/- ((Stock No. 030164 ; described below) and M5R-/- (Stock No. 030165).

Stock No. 030164: The M4 muscarinic receptor knockout allele has a PGK-neo cassette disrupting the Chrm4 locus. No functional M4 receptor expression is detected from the knockout allele. Homozygous mice (M4R-/-, M4-/-, mAChR4-/-) have no compensatory changes in expression level of the other G_i/o muscarinic receptor (M2). M4R-/- mice are viable, fertile and generally healthy, with adult mass ~5% less than wildtype littermates.
Homozygotes (on CF1;129) exhibit significantly increased basal locomotor activity [PMID:10468635].


The donating investigator reports no breeding abnormalities/problems when mating homozygous females with homozygous males. To date (February 2017), they observe no phenotype changes between these C57BL/6N-congenic M4R-/- mice and the same knock-out maintained on other genetic backgrounds (such as mixed CF1;129 or mixed C57BL6J ;129).

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. 030164 (C57BL/6N-congenic M4R-) 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 M4 muscarinic receptor knockout allele (M4R-, M4-, mAChR4-) was created in the laboratory of Dr. Jürgen Wess (NIH-NIDDK). A targeting vector was designed to replace a 0.55 kbp genomic fragment (encoding the region between the middle of the second transmembrane domain and the N-terminus of the third intracellular loop) of the cholinergic receptor, muscarinic 4 locus (Chrm4) on chromosome 2 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 CF-1 (Crl:CF1) females for germline transmission. The M4R- 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: Chrm4^tm1Jwe
Name: targeted mutation 1, Jurgen Wess
MGI accession ID: MGI:2155567
Generation method: Targeted
Attributes: Null/Knockout
Synonyms: M4 -; M4 KO; M4R^-
Marker symbol: Chrm4
Marker name: cholinergic receptor, muscarinic 4
Marker synonyms: Chrm-4; HM4; M4; M4R; muscarinic acetylcholine receptor 4
Chromosome: 2
Strain of origin: 129S6/SvEvTac
Molecular note: A genomic fragment containing sequences encoding the region between the second transmembrane loop and the third intracellular loop was replaced by a neomycin resistance cassette.