This Elovl4del targeted mutation strain exhibits homozygous perinatal lethality, defective epidermal permeability barrier, and progressive retinal photoreceptor degeneration, and is useful in studies of Stargardt-like macular degeneration and progressive retinal degeneration.
Radha Ayyagari, UCSD
The Elovl4 gene encodes a is required for the synthesis of very long chain saturated fatty acids and very long chain polyunsaturated fatty acids (chain length longer
than C > 26). Mutations and small deletions in the human ELOVl4 gene are associated with Stargardt-like macular dystrophy (STGD3) and autosomal dominant Stargardt-like macular dystrophy (ADMD), also referred to as autosomal dominant atrophic macular degeneration. These mice carry a targeted mutation of the Elovl4 gene in which a 5bp deletion was introduced in exon 6, which is equivalent to a known human mutation.
Mutant gene products (mRNA and protein) are detected by qRT-PCR and Western blot analysis of skin from homozygous pups.
Mice that are heterozygous for the targeted mutation are viable and fertile. Homozygotes die a few hours after birth. At birth homozygous mice exhibit scaly, wrinkled skin, with severely compromised epidermal permeability barrier function.
Heterozygotes have lower levels of long chain fatty acids in retinal tissue compared to wildtype controls. As early as 2 months of age, ultrastructural abnormalities are observed in cone photoreceptors. As the mice age, there is progressive accumulation of lipofuscin in retinal pigment epithelium (RPE) and subretinal deposits, debris in the subretinal space and vacuoles in the RPE.
By 6 months, heterozygotes exhibit a significant loss of cone photoreceptors. In mutant mice 8 months in age, electroretinograms (ERGs) are abnormal, with elevated b- and a-wave amplitudes.
At approximately 10 months of age, rod outer segments appear shortened.
A targeting vector designed by Dr. Radha Ayyagari (University of Michigan) containing floxed NEO cassette was used to insert a 5 bp-deletion (AACTT) in exon 6 (using site-directed mutagenesis) of the Elovl4 gene. The construct was electroporated into unspecified 129/SvEv derived embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting chimeric animals were crossed to C57BL/6J mice. The floxed NEO cassette was removed by breeding the mice with a Cre deleter strain on the C57BL/6 background. The mice were crossed to C57BL/6J for one generation.
Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).
|Allele Name||targeted mutation 1, Radha Ayyagari|
|Allele Type||Targeted (Hypomorph)|
|Allele Synonym(s)||E_mut-; Elovl4del|
|Gene Symbol and Name||Elovl4, elongation of very long chain fatty acids (FEN1/Elo2, SUR4/Elo3, yeast)-like 4|
|Strain of Origin||129S/SvEv|
|Molecular Note||A 5 bp deletion was engineered in exon 6. A floxed neo was included in the cassette and subsequently removed via cre expression. Western blot confirmed the presence of mutant protein.|
When maintaining a live colony, heterozygous mice may be bred together, to wildtype siblings, or to C57BL/6J inbred mice (Stock No. 000664). Homozygotes are not viable, dying a few hours after birth.
When using the E_mut+/- mouse strain in a publication, please cite the originating article(s) and include JAX stock #027977 in your Materials and Methods section.