Transgenic and Targeted Mutagenesis Laboratory
The primary mission of the Northwestern University Transgenic and Targeted Mutagenesis Laboratory (TTML) is to provide a centralized infrastructure with both the facilities and technical expertise needed for the production of genetically engineered mouse lines for investigators on the Evanston campus, in the Feinberg School of Medicine, the Lurie Cancer Center, and the Stanley Manne Children’s Research Institute. The core continually evaluates and develops newly emerging technologies to extend the breadth of our scientific as well as technical expertise. The TTML provides a wide repertoire of transgenic-related technologies to investigators working with genetically modified mice including the generation of mutant lines using a variety of genome editing methodologies; the global import and recovery of mutant lines from frozen material or targeted embryonic stem cell lines; cryopreservation; and the safe, economical long-term maintenance of cryopreserved mouse lines.
- Pronuclear Microinjection
Transgenic mice are generated by standard pronuclear microinjection of purified plasmid-based or BAC DNA into single-cell fertilized B6/J or B6SJL/J mouse zygotes to generate transgenic founder lines that carrying multiple copies of randomly integrated DNA.
- Genome editing mutagenesis directly in the embryo
Newer gene editing technologies such as CRISPR allow the generation of more sophisticated and complex mouse models. Introduction of gene editing reagents (Cas9, guide RNA, repair template) directly into zygotes is an efficient method for generating KO mutations, point mutations and small insertional KI models, large deletions, and conditional alleles. Materials can be provided by the investigator or generated entirely through the core.
- Gene Targeting
TTML has a fully functional ES core lab and provides full scale ES cell services, from targeting design to confirmation of correctly targeted clones. Both C57BL/6N and 129-derived ESC lines with proven pluripotency are available for gene targeting projects. CRISPR-mediated gene editing in ES cells is an alternative method for projects that do not work well in the embryo. Gene editing in ESCs offers an important alternative to embryo injection, in which, as of yet, the size of the mutation is still limiting. Additionally, investigators studying differentiation pathways have the option of deriving de novo ES cell lines from their mutant mouse lines through our core.
- ES cell Microinjection
Targeted ES cells, generated from our ESC core, purchased from international consortiums, or generated in the investigators lab, are expanded, frozen, stored long-term in liquid nitrogen dewars and injected into blastocysts to create chimeric mice. Through international consortiums, this service gives NU investigators access to pre-existing knockout models of virtually every single gene and TTML provides assistance in the evaluation and acquisition of lines from these consortiums.
- Molecular Mutagenesis Strategy and Design
The Molecular Mutagenesis Strategy and Design lab was developed to provide full scale mouse modeling services, and provide NU investigators access to the most current genomic engineering technologies. Investigators meet with TTML staff to discuss the scientific aims of the project, mouse model options, and customized mutagenesis strategy design to best achieve project goals. Technical services provided through this lab encompass guide RNA selection and editing activity assessment in blastocysts (for gene editing projects); appropriate repair template design and synthesis; preparation of reagents for injection; custom genotyping design; and founder identification and mutation confirmation through PCR, and sequencing. Consultation and technical support is provided at multiple points during the project, from project initiation through F1 generation.
These services include both the transport and/or recovery of mouse lines from germplasm, and the cryopreservation and storage of mouse lines as germplasm. This core capability not only provides a portal for the sharing of mouse resources with collaborators worldwide, but also serves as a mechanism for the efficient storage of embryos for future microinjection or other uses. All lines are tested to live birth and stored in duplicate dewars in different locations for ensure future recovery of lines. To date, the core has cryopreserved and is maintaining over 700 lines. Cryopreserved or cold-shipped germplasm can be shipped to, or received from collaborators/consortiums across the globe. In coordination with our animal facility, mouse lines can also be imported and rederived from live embryos sent overnight, freshly isolated cold-shipped epididymis, freshly isolated sperm or live mice through the Cryobiology Lab.
All manuscripts and grants presenting work supported by this core should include the following acknowledgement:
"This work was supported by the Northwestern University Transgenic and Targeted Mutagenesis Laboratory and a Cancer Center Support Grant (NCI CA060553)."