B6.129S-Sag^tm1Jnc Tg(Rho-Sag*)50Seva/Mmjax

Stock number: 017753
Research areas: Sensorineural Research

Description

Sag -/- (retinal S-antigen) mice develop disorganized photoreceptors and retinal degeneration when raised in cyclic light, when combined with the high-expressing (3A-50) mutant arrestin (Sag) transgenics, the transgene rescues a portion of the KO phenotype preventing photoreceptor loss, but does not return outer segment length completely to wild-type levels.

This mutant mouse strain may be useful in studies of retinal degeneration, light-dark adaptation and G protein-coupled receptor signaling.

Detailed description

Retinal S-antigen (Sag or arrestin) has a high affinity for phosphorylated rhodopsin, but a low affinity for unphosphorylated rhodopsin. Arrestin binds to phosphorylated rhodopsin and blocks interaction with the G protein transducin, halting the phototransduction cascade.Mice that are homozygous for the targeted mutation develop disorganized photoreceptors and retinal degeneration when raised in cyclic light. Retinal degeneration is characterized by a progressive decrease in photoreceptor outer segment (OS) length and by progressive thinness of the outer nuclear layer (ONL). The 3A-50 transgene is altered to bind unphosphorylated rhodopsin and expresses mutant arrestin at 50% of wild type. When Sag -/- mice are combined with the low-expressing (3A-50) mutant arrestin (Sag) transgenics, the transgene rescues a portion of the KO phenotype preventing photoreceptor loss, but does not return OS length completely to wild-type levels.

This mutant mouse strain may be useful in studies of retinal degeneration, light-dark adaptation and G protein-coupled receptor signaling.

Development

The transgenic construct contains three amino acid substitutions - Leu374Ala, Val375Ala, and Phe376Ala - introduced into the mouse retinal S-antigen (arrestin) coding sequence under the direction of the opsin promoter. The amino acid substitutions replace the three bulky hydrophobic residues that anchor the C tail to the body of the molecule with alanines. The transgene was microinjected into fertilized C57BL/6 oocytes and founder mice were crossed to C57BL/6 mice for an unknown number of generations. Founder line 50 expresses arrestin at 50% of wild type. Mice were crossed to B6.129S-Sag^tm1Jnc mice to generate mice that are heterozygous for the targeted mutation and hemizygous for the transgene. The colony was maintained as a backcross to C57BL/6. Upon arrival, mice were bred to C57BL/6J mice to establish the colony.

Allele

Symbol: Sag^tm1Jnc
Name: targeted mutation 1, Jeannie Chen
MGI accession ID: MGI:2388373
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Sag
Marker name: S-antigen, retina and pineal gland (arrestin)
Chromosome: 1
Strain of origin: 129S/SvEv
Molecular note: Part of the 5' promoter and exons 1 and 2 were replaced with a neomycin resistance cassette via homologous recombination. Gene expression was undetectable in rod cells of homozygous mutant animals as shown by Western blot analysis.

Allele

Symbol: Tg(Rho-Sag*)50Seva
Name: transgene insertion 50, Vsevolod Gurevich
MGI accession ID: MGI:5301173
Generation method: Transgenic
Attributes: Inserted expressed sequence
Marker symbol: Tg(Rho-Sag*)50Seva
Marker name: transgene insertion 50, Vsevolod Gurevich
Chromosome: UN
Strain of origin: C57BL/6
Expressed genes: Sag,S-antigen, retina and pineal gland (arrestin),mouse, laboratory
Molecular note: The transgenic construct contains three amino acid substitutions (Leu374Ala, Val375Ala, and Phe376Ala) introduced into the mouse retinal S-antigen (arrestin; (GenBank M24086)) coding sequence under the direction of the mouse rod opsin promoter. Line 1 and 2 with moderate and high expression were generated from founders 3A50 and 3A240, respectively.