GENE KICKED MOUSE: KNOCK OUT MOUSE AND ITS APPLICATION

A knockout mouse is a laboratory mouse in which genes are inactivated, or "knocked out," an existing gene by replacing it or disrupting it with an artificial piece of DNA. The 2007 Nobel Prize in physiology or medicine is awarded to Drs Mario R. Capecchi, Martin J. Evans and Oliver Smithies for their discoveries of principles for introducing specific gene modifications in mice by using embryonic stem cells. Progress to gene targeting using embryonic cell was developed by Evans and his co-workers. Ingenious development of gene targeting has been made by introducing recognition sites for the enzyme Cre recombinase, called loxP sites, into existing genes. When mice carrying such "floxed" genes are mated with transgenic mice expressing Cre recombinase, the target gene of the offspring is modified through Cre action. Gene targeting has transformed scientific medicine by permitting experimental testing of hypotheses regarding the function of specific genes. The first area to which experimental geneticists turned their attention after the birth of gene targeting in mammals was monogenic diseases. Gene targeting has been exceptionally useful in cancer research. A large number of protooncogenes, tumor suppressor genes, angiogenetic factors etc have been targeted in different tissues in mice to shed light on the induction and spreading of tumours. Gene-targeted mouse models have also become increasingly important in studies of host defense against pathogens. Gene targeted mice have become indispensable in virtually all aspects of medical research