Purchase this article with an account.
K. Gollomp, L. Feiner, P. Ojha, D.C. Richa, N. Esumi, D. Zack, M. Navaratnarajah, E. Pierce, J.L. Dunaief; Generation of Cre Transgenic Mice With Rpe–Specific and Photoreceptor–Specific Expression for Conditional Knockouts Using the Cre–loxp System . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4160.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The Cre–loxP system can be used to create conditional knockout mice. Our goal is to create photoreceptor–specific and RPE–specific Cre expressing transgenic mice that can be used to generate cell–type specific knockouts. This will facilitate testing of cell–autonomous gene function and enable study of genes whose systemic absence is lethal. A new transgenic mouse line with VMD2 promoter driven Cre expression allows the conditional removal of genes in the RPE. Unfortunately, high level, persistent expression of Cre has been shown to be toxic to photoreceptors. In order to induce non–toxic Cre expression in the photoreceptors rhodopsin–Cre transgenic mice have been generated in which the transgene is flanked by loxP sites, leading to the excision of the transgene upon Cre–recombinase expression.
Mice expressing Cre–recombinase in the photoreceptors were prepared by placing the Cre gene behind the rhodopsin promoter. LoxP sites were inserted flanking the transgene. RPE specific Cre expression was accomplished by placing Cre behind the VMD2 promoter. Cre expression was assessed by crossing with the RosaLacZ reporter strain and by IHC. Retinal function was assessed using ERG. Retinal structure was evaluated using fundus exam and histology.
LoxP–flanked rhodopsin–Cre mice were produced to generate temporally limited Cre expression.These mice have functional Cre limited to photoreceptors as evidenced by activation of LacZ in a cross with the RosaLacZ strain. VMD2–Cre mice have Cre activity in patches of RPE cells and isolated cells in the GCL. The number of Cre positive RPE cells varies among mice derived from a single founder. Retinal degeneration has not been found in 1 year old specimens from rhodopsin–Cre or VMD2–Cre mice.
The initial observation of mice with loxP mediated limitation of Cre–recombinase expression suggests that this approach prevents photoreceptor toxicity in transgenic rhodopsin–Cre mice.The VMD2–Cre line has patchy RPE Cre expression, which has certain advantages, but additional lines have been generated and are being tested for Cre expression. It is hoped that these animals will facilitate the creation of mouse models with conditional gene excision in either the photoreceptors or the RPE.
This PDF is available to Subscribers Only