STOCK Opn4^{tm4.1(DTA)Saha}/J

Stock number: 035928
Product name: Opn4^aDTA
Research areas: Neurobiology Research, Research Tools

Description

Opn4^aDTA knock-in/knock-out mice express an attenuated diphtheria toxin (aDTA) under the direction of the Opn4 promoter, resulting in the ablation of intrinsically photosensitive retinal ganglion cells (ipRGCs) in adult mice.

Detailed description

Opn4^aDTA knock-in/knock-out mice express an attenuated diphtheria toxin subunit alpha (DTA) sequence under the direction of the opsin 4 (melanopsin) (Opn4) promoter. Opn4 encodes a photoreceptive opsin protein that is part of the G protein-coupled receptor family. Expressed within the melanopsin-expressing retinal ganglion cells and amacrine cell layers of the retina, OPN4 is required for the regulation of circadian rhythms as a result of photosensitivity. Homozygous mice are viable and fertile. These mice express an attenuated version of diphtheria toxin (aDTA), resulting in the ablation of M1 intrinsically photosensitive retinal ganglion cells (ipRGCs) only in adult mice older than 60 days of age. Homozygous Opn4^aDTA/aDTA mice show more substantial ipRGC loss than heterozygous Opn4^aDTA/+ mice.

Of note, a similar strain expressing full strength DTA (DTA) under control of the same promoter is available as Stock No. 035927. Expression of DTA in Opn4^DTA mice results in ablation of M1, M2 and M3 ipRGCs at early postnatal stages.

Development

The Opn4^aDTA targeting construct was designed to replace exons 1-9 of the opsin 4 (melanopsin) (Opn4) gene with an attenuated version of diphtheria toxin A (DTA) subunit sequence and a loxP-flanked neomycin resistance cassette. This construct was electroporated into 129-derived embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and the resulting chimeric males were bred to C57BL/6J females. Subsequently, mice were bred to CMV-Cre mice (Stock No. 006054) to remove the neo cassette. Mice were maintained on a mixed genetic background by breeding to B6129SF1/J mice (Stock No. 101043) by the donating lab. Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).

Allele

Symbol: Opn4^{tm4.1(DTA)Saha}
Name: targeted mutation 4.1, Samer Hattar
MGI accession ID: MGI:7254852
Generation method: Targeted
Attributes: Inserted expressed sequence
Synonyms: Opn4^aDTA
Marker symbol: Opn4
Marker name: opsin 4 (melanopsin)
Marker synonyms: 1110007J02Rik; MOP
Chromosome: 14
Strain of origin: 129
Molecular note: An attenuated diphtheria toxin A gene and loxP-flanked neo cassette were inserted immediately downstream of the start methionine codon replacing the coding region through part of exon 9. Expression of this allele results in the ablation of intrinsically photosensitive retinal ganglion cells. Flp-mediated recombination removed the FRT-flanked neo cassette.
General note: The version of this allele that contains the neomycin selection cassette, Opn4^tm4(DTA)Saha, has been analyzed.