FUNCTIONAL GENOMICS IN MICE BY TAGGED SEQUENCE MUTAGENESIS

Most mammalian genes will soon be characterized as cDNA sequences with little information about their function. To utilize this sequence inf ormation for large-scale functional studies,a gene trap retrovirus shu ttle vector has been developed to disrupt genes expressed in murine em bryonic stem (ES) cells. A library of mutant clones was isolated, and regions of genomic DMA adjacent to 400 independent provirus inserts we re cloned and sequenced. The flanking sequences, designated 'promoter- proximal sequence tags', or PSTs, identified 63 specific genes and ano nymous cDNAs disrupted as a result of virus integration. The efficienc y of tagged sequence mutagenesis suggests that many of the 10,000-20,0 00 genes expressed in ES cells can be targeted, providing defined muta tions for the analysis of gene functions in vivo. In addition, PSTs pr ovide the first expressed sequence tags derived from genomic DNA, and define gene features such as exon boundaries and promoters that are mi ssing from cDNA sequences.