Jackson Lab Receives New KOMP2 Grant

The NIH has awarded $28.3 million to the Jackson Laboratory (JAX) in Bar Harbor, ME, to expand the Knockout Mouse Production and Phenotyping Project (KOMP2) over the next 5 years. Instead of using embryonic stem cell (ESC) lines, researchers at JAX plan to capitalize on CRISPR/Cas9, the powerful gene editing technology that debuted in 2014, to generate new knockout mouse strains.

In 2006, the International Knockout Mouse Consortium began the mammoth task of creating knockout mutations in ESCs for each of the approximately 20,000 genes shared with humans. The International Mouse Phenotyping Consortium (IMPC) was formed in 2011 to build on this effort by producing and phenotyping knockout mouse strains from 5,000 ESC lines.

KOMP2 was launched as part of the IMPC, with the NIH supporting three U.S. institutions—JAX; Baylor College of Medicine in Houston, TX; and the University of California, Davis, in Sacramento—in making half of these strains (833 each). The new grant kicks off KOMP2′s next phase, in which JAX will produce and phenotype another 1,000 knockout mouse strains, says principal investigator Robert Braun, PhD.

Stephen Murray, PhD, another principal investigator, explains that generating knockout mice from genetically modified ESCs is laborious and expensive: Selecting ESC clones to inject into mouse blastocysts is just one of multiple steps with “lots of checks and balances to ensure quality control.” Because long-term cell culture can render ESCs karyotypically unstable or cause loss of pluripotency, whether the desired mutation is successfully transmitted to the mouse germline is not guaranteed.

By contrast, CRISPR/Cas9 is used much earlier in embryogenesis—researchers can directly tweak single-cell zygotes, ensuring a much higher germline transmission rate. Fewer reagents are involved, too. “We can get a specific knockout mouse in one third of the time, at one third of the cost,” Murray says.

“The money saved can be applied toward phenotyping these mice, which hasn't gotten less expensive,” says Karen Svenson, PhD, KOMP2′s third principal investigator. She directs JAX's high-throughput phenotyping pipeline, where knockout mice undergo different tests assessing behavior, metabolism, and sleep, among other clinical traits. Biological and functional data from each strain are then stored in a publicly accessible database (www.mousephenotype.org).

Carol Bult, PhD, deputy director of JAX's cancer center, notes that the wealth of phenotypic data from this pipeline may aid in the discovery of early markers of cancer susceptibility. JAX researchers are using KOMP2 mouse strains to investigate various cancer-related questions, she says, including the role of heat shock proteins in tumor growth. They're also interested in exploring the sequence of mutations that initiate acute myeloid leukemia and drive its progression.

In addition, NCI-funded researchers across the country have ordered more than 500 strains from JAX to conduct their own studies.

Previously, Braun adds, JAX's knockout mice were sacrificed at 18 weeks after being extensively phenotyped—a very young age by which cancer seldom develops.“Now, we've been funded to age out 15% of our strains to 18 months, so we may see spontaneous tumors forming in these mice, which will be exciting to explore.”

Building this comprehensive catalog of a mammalian genome requires a global effort, Braun emphasizes. “We're not working in a vacuum. It's been a joy collaborating with IMPC members over the years; we'd welcome additional partners in this endeavor.” –Alissa Poh

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