B6(Cg)-Rbp3^em1Jmni/J

Stock number: 039716
Product name: RBP3-floxed
Strain synonyms: IRBP^fl
Research areas: Cancer Research, Research Tools, Sensorineural Research

Description

The RBP3-floxed allele has loxP sites flanking exon 1 of the mouse retinol binding protein 3, interstitial (Rbp3; also called interphotoreceptor retinoid binding protein, IRBP) gene - enabling Cre recombinase-dependent Rbp3 knock-out. These mice may be useful in studies of eye development, retinal degeneration, and myopia.

Importantly, the donating laboratory noted that the loxP sites are far apart such that recombination events can occur when breeding these mice to homozygosity. Therefore, it is highly recommended that whenever these mice are being bred as heterozygotes that both loxP sites are confirmed by genotyping.

Detailed description

The Interstitial retinal binding protein 3 (IRBP; coded by Rbp3 gene) is a large glycoprotein that binds retinoids and fatty acids and transports retinoids between the retinal pigment epithelium and the photoreceptors, mediating cone pigment regeneration.

The RBP3-floxed mice have a conditional, Cre recombinase-dependent knock-out of the mouse retinol binding protein 3, interstitial (Rbp3) gene. Homozygous RBP3-floxed mice are viable and fertile. After Cre expression, the sequence flanked by the loxP sites is deleted. The residual parts of the Rbp3 gene lack a functional promoter, cis-elements, and functional transcription start site. These RBP3-floxed mice may be useful for studying the temporal and spatial effects of knocking out RBP3 on eye and retinal development and onset of age-related retinal degeneration, and myopia.

The donating laboratory reported that the conditional knock-out of the floxed allele in the retina by crossing to the whole retina Cre driver line (mRx-CRE: Tg(Rax-cre)1Zkoz) resulted in the development of myopia and slow retinal degeneration. However, when crossed to rod-specific Cre-expressing mice (Rho-iCre75: Tg(Rho-icre)1Ck), it showed significant retinal functional losses without myopia.

Development

Exon 1 of the Rbp3 gene was flanked by loxP sites using a combination of targeting in C57BL/6J-derived ES cells. First, a 3' loxP site was inserted 3117 bp downstream from the transcription start site in the first intron. Chimeric founder mice were bred to C57BL/6J Flp-deleter females to remove an FRT-flanked selection cassette. Next, CRISPR/Cas9 methodologies were used to introduce a second 5' loxP site upstream of exon 1 at -643 bp upstream from the transcription start site in heterozygous zygotes derived from IVF of wildtype C57BL/6J eggs and sperm having a single 3' loxP in the Rbp3 gene. The resulting mice with floxed Rbp3 gene were mated to C57BL/6J mice to establish a colony and were bred to homozygosity. Mice were confirmed to have both loxP sites by PCR at each locus through the establishment of the founder line. DNA sequencing was performed to confirm the correct insertion of the loxP sites. The donating laboratory noted that these loxP sites are far apart such that recombination events can occur when breeding these mice to homozygosity. Therefore, it is highly recommended that whenever these mice are being bred as heterozygotes that both loxP sites are confirmed by genotyping. The donating laboratory reports this mutant strain was maintained on a C57BL/6J genetic background prior to sending males to The Jackson Laboratory in 2024. Upon arrival, sperm was cryopreserved. Cryorecovery/live colony development will involve C57BL/6J (Stock No. 000664).

Allele

Symbol: Rbp3^em1Jmni
Name: endonuclease-mediated mutation 1, John M Nickerson
MGI accession ID: MGI:7710916
Generation method: Endonuclease-mediated
Attributes: Conditional ready (e.g. floxed)
Synonyms: IRBP^fl
Marker symbol: Rbp3
Marker name: retinol binding protein 3, interstitial
Marker synonyms: D10S64; D10S65; D10S66; IRBP; Rbp-3; RBPI; RP66
Chromosome: 14
Strain of origin: C57BL/6J
Molecular note: Exon 1 of the Rbp3 gene was flanked by loxP sites using a combination of targeting in C57BL/6J derived ES cells and subsequent CRISPR/cas9 methodologies to introduce additional loxP sites. The allele Rbp3^tm1.1Jmni created a 3' loxP site at 3117 bp downstream from the transcription start site in the first intron. Then CRISPR/cas9 methodologies were used to introduce a second 5' loxP site upstream of exon 1 at -643 bp upstream from the transcription start site in heterozygous zygotes derived from IVF of wildtype C57BL/6J eggs and sperm having a single 3' loxP in the Rbp3 gene Rbp3^tm1.1Jmni.