Cre recombinase expression or topical tamoxifen treatment do not affect retinal structure and function, neuronal
S K Boneva1, T R Groß1, A Schlecht1
1Institute of Human Anatomy and Embryology, University of Regensburg, Germany.
Abstract:
Mice with a constitutive or tamoxifen-induced Cre recombinase (Cre) expression are frequently used research tools to allow the conditional deletion of target genes via the Cre-loxP system. Here we analyzed for the first time in a comprehensive and comparative way, whether retinal Cre expression or topical tamoxifen treatment itself would cause structural or functional changes, including changes in the expression profiles of molecular markers, glial reactivity and photoreceptor vulnerability. To this end, we characterized the transgenic α-Cre, Lmop-Cre and the tamoxifen-inducible CAGG-CreER™ mouse lines, all having robust Cre expression in the neuronal retina. In addition, we characterized the effects of topical tamoxifen treatment itself in wildtype mice. We performed morphometric analyses, immunohistochemical staining, in vivo ERG and angiography analyses and realtime RT-PCR analyses. Furthermore, the influence of Cre recombinase or topical tamoxifen exposure on neuronal vulnerability was studied by using light damage as a model for photoreceptor degeneration. Taken together, neither the expression of Cre, nor topical tamoxifen treatment caused detectable changes in retinal structure and function, the expression profiles of investigated molecular markers, glial reactivity and photoreceptor vulnerability. We conclude that the Cre-loxP system and its induction through tamoxifen is a safe and reliable method to delete desired target genes in the neural retina.
Insights
The Cre-loxP system and tamoxifen are safe for retinal research. Neither Cre expression nor tamoxifen treatment altered retinal structure, function, or photoreceptor vulnerability in mice.
Area of Science:
- Ophthalmology
- Neuroscience
- Genetics
Background:
- Conditional gene deletion using the Cre-loxP system is crucial for research.
- Cre recombinase (Cre) expression or tamoxifen induction are common methods.
- Potential retinal side effects of these methods require thorough investigation.
Purpose of the Study:
- To comprehensively evaluate the safety of retinal Cre expression and topical tamoxifen treatment.
- To assess structural and functional changes in the retina.
- To determine effects on molecular markers, glial reactivity, and photoreceptor vulnerability.
Main Methods:
- Characterization of transgenic mouse lines (α-Cre, Lmop-Cre, CAGG-CreER™) with retinal Cre expression.
- Topical tamoxifen treatment in wildtype mice.
- Morphometric analysis, immunohistochemistry, in vivo ERG, angiography, and RT-PCR.
- Photoreceptor vulnerability assessment using a light damage model.
Main Results:
- No detectable changes in retinal structure or function were observed.
- Expression profiles of investigated molecular markers remained unchanged.
- Glial reactivity and photoreceptor vulnerability were not affected by Cre expression or tamoxifen.
Conclusions:
- The Cre-loxP system and tamoxifen induction are safe and reliable for conditional gene deletion in the neural retina.
- These methods do not induce adverse structural or functional retinal changes.
- Researchers can confidently use these tools for genetic manipulation in retinal studies.
