B6.129S6(Cg)-Htr1a^tm4.1Rhn/J

Stock number: 040021
Product name: 5ht1aflox
Strain synonyms: fl1A
Research areas: Neurobiology Research, Research Tools

Description

5ht1aflox conditional knock-out mice have the 5-hydroxytryptamine (serotonin) receptor 1A (Htr1a) gene flanked by loxP sites. The Htr1a gene encodes a G protein-coupled receptor that mediates inhibitory neurotransmission. These mice may be useful for studying serotonin receptor signaling.

Detailed description

5ht1aflox conditional knock-out mice have loxP sites inserted to flank the entire 5-hydroxytryptamine (serotonin) receptor 1A (Htr1a) gene, allowing for the selective knock-out of the Htr1a gene in tissues expressing Cre recombinase. When Cre recombinase is present, it excises this region, leading to a knock-out of Htr1a. Additionally, the mice express a yellow fluorescent protein (YPet) under the control of the Htr1a promoter, which serves as a reporter to visualize Cre-mediated recombination. Homozygotes are viable and fertile and show no overt behavioral or physiological abnormalities. These mice may be useful for studying serotonin receptor signaling.

Development

The targeting vector consisted of a homology arm with loxP, FRT, PGK-EM7-Neo minigene, FRT, loxP, YPet cDNA (YPet is a modified yellow fluorescent protein), SV40 polyadenylation signal, 3' homology arm, and diphtheria toxin A subunit (DTA). The first loxP site was inserted just upstream of the coding region, and the second loxP site was inserted after the Htr1a polyadenylation signal. A modified yellow fluorescent protein, YPet, cDNA was inserted downstream of the 3' loxP site such that when the floxed region is removed, YPet is expressed under the endogenous Htr1a promoter. The linearized targeting vector was electroporated into 129S6/SvEvTac-derived CSL3 embryonic stem (ES) cells, and G418-resistant clones were selected. Southern blots were then performed to verify the homologous recombination. The recombinant ES cells were then injected into recipient blastocysts to obtain chimeric mice. Germline-transmitted founder mice were then crossed with ROSA-Flpe (Gt(ROSA)26Sor^tm1(FLP1)Dym) mice to remove the PGK-EM7-Neo minigene through FLP-FRT recombination. The offspring of these crosses were backcrossed to C57BL/6 mice for more than five generations to breed out the ROSA-Flpe allele (see SNP note below). Then, heterozygous mice were intercrossed to produce homozygous mice and maintained on a C57BL/6 genetic background by the donating laboratory. Upon arrival at The Jackson Laboratory, sperm were cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J (Stock No. 000664) oocytes.

In 2025, a 48 SNP (single nucleotide polymorphism) panel analysis, with 43 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the males sent to The Jackson Laboratory Repository. One of the 43 markers throughout the genome were segregating with 129. Also, two of the 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6N;C57BL/6J genetic background.

Allele

Symbol: Htr1a^tm4.1Rhn
Name: targeted mutation 4.1, Rene Hen
MGI accession ID: MGI:7484513
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Reporter; No functional change
Synonyms: fl1a
Marker symbol: Htr1a
Marker name: 5-hydroxytryptamine (serotonin) receptor 1A
Marker synonyms: 5HT1a; 5-HT1A; 5-HT-1A; 5-HT1A receptor; ADRB2RL1; ADRBRL1; G-21; Gpcr18; PFMCD; RAT5HT1A
Chromosome: 13
Strain of origin: 129S6/SvEvTac
Molecular note: The single exon and the 3’ untranslated region containing the polyadenylation signal were flanked by loxP sites. A modified yellow fluorescent protein, YPet, cDNA was inserted downstream of the 3’ loxP site such that when the floxed region is removed, YPet is expressed under the endogenous Htr1a promoter. An inserted FRT-flanked PGK-EM7-Neomycin minigene was removed via flp-mediated recombination.