May 2004
Volume 45, Issue 13
ARVO Annual Meeting Abstract  |   May 2004
A transgenic X. laevis system for studying retinal degeneration caused by localization–defective rhodopsin mutants.
Author Affiliations & Notes
  • O.L. Moritz
    Ophthalmology, University of British Columbia, Vancouver, BC, Canada
  • B.M. Tam
    Ophthalmology, University of British Columbia, Vancouver, BC, Canada
  • Footnotes
    Commercial Relationships  O.L. Moritz, None; B.M. Tam, None.
  • Footnotes
    Support  CIHR MOP–64400; FFB Canada; MSFHR; KKF
Investigative Ophthalmology & Visual Science May 2004, Vol.45, 3606. doi:
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      O.L. Moritz, B.M. Tam; A transgenic X. laevis system for studying retinal degeneration caused by localization–defective rhodopsin mutants. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3606.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract: : Purpose: The C–terminus of rhodopsin contains an outer segment localization signal. Several RP–causing mutations disrupt this signal, resulting in delocalization of rhodopsin to the plasma membrane of the inner segment. In order to determine the mechanisms of cell death resulting from this delocalization we have modeled these disorders in transgenic X. laevis. Methods: We constructed transgenes based on the X. laevis rhodopsin cDNA and promoter, incorporating a mutation that introduces an antibody epitope, which allows us to distinguish the resulting protein from endogenous X. laevis rhodopsin. Transgenes were constructed with or without a C–terminal deletion, and with or without mutations designed to interfere with rhodopsin signal transduction. Transgene constructs also incorporated a second gene that confers resistance to the antibiotic G418. Large numbers of transgenic embryos were generated by nuclear transplantation, and identified by G418 selection. At 14 days post fertilization, retinal degeneration was assessed and correlated with transgene expression levels using a dot blot method. Contralateral eyes were studied by confocal microscopy. Results: Retinal degeneration was induced in a significant proportion of animals expressing truncated rhodopsins by 14 days post–fertilization. The severity of retinal degeneration was correlated with transgene expression level. This correlation was not observed in animals expressing a control transgene. Confocal microscopy of antibody labeled sections of transgenic retinas showed that the truncated rhodopsins were delocalized to rod inner segment membranes. Conclusions: We have developed a novel animal model of retinal degeneration, which is unique in that 1) primary transgenic animals are studied, and 2) the effects of varying levels of transgene expression can be determined. Using this model in combination with mutations that disrupt rhodopsin signal transduction, we hope to obtain important insights into the pathways underlying RP.

Keywords: retinal degenerations: cell biology • photoreceptors • transgenics/knock–outs 

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