Shared Resource: Transgenic and Knockout Mouse

Mei Lang Flowers, research technician II, harvests mouse embryos for a microinjection session.Transgenic mice genetically engineered to develop cancer is a relatively new technology first realized during the 1980s. Since that time genetically modified mice have been used extensively in research as models for human disease. Knockout mice lacking tumor suppressing genes make for good models for human cancer.

Attesting to the scientific impact of this technology provided by Duke’s Transgenic and Knockout Mouse Shared Resource, over the past funding period using mice generated by the resource, more than 325 Duke peer-reviewed research papers have been published. (can this stat by updated or elevated?)

Cheryl Bock, transgenic facility manager, discusses experimental conditions with Scott Soderling, PhD, director, during a microninjection session of CRISPR regents into mouse embryos to make a knockin mouse model for a DCI member's cancer research project.“The Transgenic Core supports DCI investigators by providing a full range of options for generating custom mice genetically altered for their cancer research,” said Scott Soderling, PhD, director of Transgenic and Knockout Mouse Shared Resource. “Users can literally name their gene of interest and the type of alteration they desire and received their mice. For projects handled by the core from start to finish to generate approximately a 98 percent success rate.”

The shared resource specializes in the microinjection of DNA/RNA constructs into the pronucleus of fertilized mouse embryos and the genetic manipulation of pluripotent mouse embryonic stem cells (ESCs). DNA microinjection produces founder animals known as “transgenic mice.” Introduction of embryonic stem cells with altered genes into the blastocyst produces animals that are colloquially recognized as “gene targeted mice.” Using ESCs, the resource makes mice with pint mutations, null alleles and deletions (knockout mice), conditional mutations and gene exchanges.

Gary Kucera uses a multichannel pipettor to set up a 96 well plate for PCR analysis DNA from ES targeted clones.“Our shared resource provides vertebrate model organisms to study the complex disease of cancer in ways that cell culture and other in vitro systems are cannot,” said facility manager Cheryl Bock, on staff at Duke since 1984. “Beginning with a consultation on design, we have services to carry the project all the way through breeding and cryopreserving these valuable living reagents.”

Transgenic and Knockout Mouse Shared Resource recently added a host of new services using CRISPR-mediated genome editing. The technology can rapidly generate mice with a range of genetic with a range of genetic modifications.  The resource has successfully produced knockouts, point mutations and knockin using leading-edge in vivo editing by injection of CRISPR constructs into mouse embryos.

“CRISPR-mediated genome editing allows us to disrupt gene function by insertions and deletions, generation of genetic point mutations, insertions of GFP or Cre and placement of LoxP sites to generate conditional knockout mice,” Soderling said. “While these techniques are very new and methods are rapidly evolving, we work with investigators to bring these cutting-edge approaches to their research projects.”

The resource is organized into three specialized teams providing BAC recombineering services, transgenic and gene targeted mouse services and rodent husbandry services. Investigators can maximize project efficiency by taking advantage of complete services -- from designing a gene mutation, targeting ESCs to producing genetically altered mice or mutating mice by direct injection of CRISPR constructs into mouse embryos, expanding and cross breeding lines and preserving the mice as frozen embryos and sperm.

Michael Flores processes experimental samples in a laminar flow hood chamber.“We work in close collaboration with basic and physician scientists to provide personalized technical support at all stages of the process,” Bock said. “Our value added is that we are available for consultation on any aspect of the project, even after we have handed off the mice to the investigator. Since study of animal models can often take a minimum of three years until publication, we serve as a repository of knowledge as lab members.”

Duke Cancer Institute member receives the lowest fees for services at all times. To initiate access to Transgenic and Knockout Mouse Shared Resource, researchers must submit a formal Service Request. The Transgenic Mouse Facility is located in the Snyderman Building at 905 South LaSalle Street. For more information, visit Duke Cancer Institute. To submit a service request, visit http://www.tmf.cancer.duke.edu/.

The Team: Scott Soderling, PhD, director; Mei Lang Flowers, research assistant II; Gary Kucera, BAC core manager; Michael Flores, laboratory research analyst; and Cheryl Bock, manager.