The Animal Modeling Core (AMC) provides comprehensive services for the design and generation of genetically engineered rat models. Our rat-modeling capabilities parallel many of the services we provide in mice, allowing investigators to take advantage of the rat as an experimental model while still accessing advanced CRISPR-Cas genome editing, targeted knock-in, transgenic, and other genetic engineering technologies.
Our team works closely with investigators to determine the most appropriate strategy based on the biological question, desired genetic modification, rat strain, experimental timeline, and downstream applications. Projects range from routine knockout and knock-in models to disease-associated variants, conditional alleles, reporter models, large DNA insertions, and other customized genomic modifications.
Project Design and Consultation
The AMC provides an initial consultation to discuss project goals and identify the most appropriate strategy for generating the desired mouse model. Considerations may include:
- Type and complexity of the desired genetic modification
- Selection of CRISPR-Cas or alternative genome-engineering strategies
- Rat strain and genetic background
- Germline versus somatic approaches
- Model validation and genotyping strategies
- Breeding requirements and experimental timelines
Our team can provide support from initial model conception and sequence design through founder generation, molecular validation, and establishment of the desired rat line.
CRISPR-Cas Genome Editing
The AMC routinely uses CRISPR-Cas genome editing to generate customized rat models directly in embryos. Applications include:
- Gene knockouts
- Point mutations and disease-associated variants
- Small and large targeted knock-ins
- Epitope and fluorescent protein tags
- Reporter alleles
- Cre and Flp recombinase knock-ins
- Conditional alleles containing loxP or FRT sites
- Humanized sequences and other customized genomic modifications
CRISPR reagents and DNA repair templates can be introduced into rat embryos using electroporation, microinjection, AAV-mediated delivery, or combinations of these approaches depending on the requirements of the project.
Complex and Targeted Knock-In Models
The AMC has expertise in developing and applying alternative strategies for challenging targeted knock-in projects in rats.
Depending on the desired modification, approaches may include single-stranded or double-stranded DNA repair templates, AAV-mediated donor delivery, optimized embryo-stage targeting, and other customized methods designed to improve targeted integration efficiency.
The optimal strategy is selected individually for each project based on the size and sequence of the desired insertion, genomic locus, and intended application.
Conditional and Tissue-Specific Rat Models
The AMC can design and generate conditional rat alleles for spatially or temporally controlled gene modification. Services include generation of floxed alleles, conditional knock-in models, recombinase-dependent reporter alleles, and other customized designs compatible with Cre- or Flp-based systems.
We can also assist investigators with model design and breeding strategies involving existing recombinase-driver rat lines when available.
AAV-Mediated and Somatic Rat Models
For some experimental questions, direct manipulation of gene expression in vivo may provide a faster or more flexible alternative to generating a permanent germline rat line.
The AMC can assist investigators with AAV-based strategies for applications such as:
- Gene overexpression
- Expression of disease-associated or engineered gene variants
- Reporter gene expression
- RNA interference and gene knockdown
- Evaluation of candidate therapeutic constructs
- Tissue- or cell type-directed expression using appropriate promoters and AAV serotypes
The AMC can assist with experimental design, construct design, vector strategy, and coordination of in vivo studies.
Transgenic Rat Production
The AMC offers traditional transgenic rat production through embryo microinjection of engineered DNA constructs. This approach can be used for projects requiring random genomic integration of transgenes or other applications for which targeted genome editing is not required.
The AMC can assist with construct design, embryo manipulation, founder identification, and molecular characterization.
Embryonic Stem Cell-Based Rat Production
Rat models can also be generated using genetically modified embryonic stem (ES) cells. The AMC can perform blastocyst injection of targeted ES cells to generate chimeric rats and can work with commercially available or investigator-provided ES cell clones.
ES cell-based approaches may be useful for selected complex alleles or projects involving existing targeted ES cell resources.
Advanced Rat Genome-Editing Technologies
AMC investigators have developed and optimized specialized approaches for challenging rat genome-engineering projects, including AAV-mediated donor delivery combined with 2-cell embryo CRISPR-Cas9 electroporation.
Explore our Technology & Innovation page to learn more about genome-editing strategies developed by the AMC.
Have a Challenging Rat Model?
Rat genome engineering can present challenges that differ from those encountered in mice, and some projects do not fit neatly into a standard knockout or knock-in workflow.
The AMC routinely works with investigators to develop customized strategies for technically challenging rat-modeling projects. Investigators are encouraged to contact us early in project development to discuss feasibility, experimental design, timelines, and potential approaches.