The team inserted newly designed DNA vectors in place of the microRNA genes, successfully knocking out about 400 so far.
"The biology of microRNAs will be revealed only when we can rigorously examine their activity, their role in individual tissues, and at specific times in development," says Professor Allan Bradley, senior author on the study and Director Emeritus of the Sanger Institute. "Our paper shows that the tools within mirKO can do that.
"We have tagged genes with a colour reporter, developed a mutation that can be induced when required and produced mice carrying mutations. This is an important proof of principle."
In previous research, Professor Bradley's team showed that a specific microRNA played a role in the development of a component of the immune system: in its absence, mice develop signs similar to those of human autoimmune disease and are less resistant to infection.
The resource is built on cassettes of genetic components that can be swapped through a technology called recombinase mediated cassette exchange (RMCE). "We have designed the targeted alleles to be adaptable in order that researchers can efficiently alter particular microRNA loci in a multitude of alternative ways to provide information additional to straightforward null mutants. In this respect we have developed a research toolbox that will help researchers define the role of microRNAs in health and disease,"says Haydn Prosser.
In one configuration the wildtype microRNA locus was reconstituted while being flanked by recombinase sites in order to facilitate time- or tissue-specific expression. A second RMCE cassette contains a gene that produces a red fluorescent protein: when this is swapped into a mutated microRNA gene, it reflects the activity of the mouse microRNA gene so its activity can be studied. The team showed that this method accurately reflected the known activity of two microRNA loci.
|Contact: Don Powell|
Wellcome Trust Sanger Institute