Predetermined chromosomal deletion encompassing the Nf-1 gene

Complex chromosomal rearrangements (deletions, inversions, translocations) are a hallmark of human tumour cells, Yet, the generation of animal models for gross chromosomal abnormalities still presents a formidable challenge. Here, we describe a versatile procedure for chromosomal engineering that wa s used to generate an ES cell line with a megabase deletion encompassing th e tumour suppressor gene neurofibromatosis-l (Nf-l) on mouse chromosome 11, which is often deleted in tumours of neural crest origin. Homologous recom bination into sites flanking Nf-1 was used to introduce artificial sequence s (triple-helix, loxP, vector backbone) that can be employed for in vitro r ecovery of intervening sequences or the generation of in viva deletions. Th is strategy may be developed into a scheme by which large chromosomal regio ns with precisely defined end points may be excised from mammalian cells an d reintroduced after suitable in vitro modification.