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J.L. Estrada, J.R. Sommer, B.E. Collins, C.A. Alexander, B. Mir, Y. Chen, K.A. Howes, J.A. Piedrahita, K. Zhang, R.M. Petters; Production of ELOVL4 Transgenic Pigs: An Animal Model for Stargardt–Like Macular Degeneration . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5814.
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© ARVO (1962-2015); The Authors (2016-present)
Mutations in the ELOVL4 gene cause a juvenile form of macular degeneration, Stargardt macular dystrophy 3 (STGD3). In order to generate an animal model which more closely mimics the pathobiology of this macular disease, we chose to generate transgenic pigs expressing the human disease–causing ELOVL4 mutations. The pig is a superior animal model for studying human retinal degenerations due to the large retinal size and anatomy, which contains a macula–like area centralis.
DNA microinjection or somatic cell nuclear transfer was used to produce transgenic pigs for two ELOVL4 mutations, the 5 bp deletion and the 270 stop mutation, under the control of a rhodopsin promoter. The 270 stop construct was fused to EYFP (270 stop–EYFP). RT/PCR, histology, direct fluorescent and immunofluorescent microscopy were performed using standard techniques.
For the 5 bp deletion construct, 3 transgenics were produced from 1305 microinjected embryos. The 270 stop–EYFP transgenics were produced by somatic cell nuclear transfer with 8 transgenic animals produced from 1400 nuclear transfer embryos. Six transgenic founder pigs have thus far been tested for germ line transmission. All have proven to be fertile and transmit the transgene with the exception of a 5 bp deletion boar, which was sterile. Based on RT/PCR analysis, all the lines tested express the transgene. Direct fluorescent microscopy analysis has indicated that the 270 stop–EYFP transgene is correctly expressed in photoreceptors only, as expected for the rhodopsin promoter. Immunohistochemical examination of Pig 63604, which was 14.5 months at the time of euthanasia, revealed some photoreceptor loss and disorganized/shortened photoreceptor outer segments. The other transgenic pig lines are currently being examined for mutant ELOVL4 expression levels and retinas examined for histopathology.
Transgenic pigs have been produced that harbor mutant forms of the gene, ELOVL4, which is known to cause Stargardt macular dystrophy 3. The transgenic pigs transmit the transgene to offspring and express it in the retina. Preliminary analysis indicates some retinal degeneration in one pig expressing the 5bp deletion at 14.5 months of age. Transgenic pigs expressing ELOVL4 mutant proteins provide a unique animal model for examining STGD3 macular pathogenesis.
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