Targeted modification of mammalian genomes

D A Sorrell, Andreas Kolb

    Research output: Contribution to journalLiterature reviewpeer-review

    91 Citations (Scopus)


    The stable and site-specific modification of mammalian genomes has a variety of applications in biomedicine and biotechnology. Here we outline two alternative approaches that can be employed to achieve this goal: homologous recombination (HR) or site-specific recombination. Homologous recombination relies on sequence similarity (or rather identity) of a piece of DNA that is introduced into a host cell and the host genome. In most cell types, the frequency of homologous recombination is markedly lower than the frequency of random integration. Especially in somatic cells, homologous recombination is an extremely rare event. However, recent strategies involving the introduction of DNA double-strand breaks, triplex forming oligonucleotides or adeno-associated virus can increase the frequency of homologous recombination.

    Site-specific recombination makes use of enzymes (recombinases, transposases, integrases), which catalyse DNA strand exchange between DNA molecules that have only limited sequence homology. The recognition sites of site-specific recombinases (e.g. Cre, Flp or Phi C31 integrase) are usually 30-50 bp. In contrast, retroviral integrases only require a specific dinucleotide sequence to insert the viral cDNA into the host genome. Depending on the individual enzyme, there are either innumerable or very few potential target sites for a particular integrase/recombinase in a mammalian genome. A number of strategies have been utilised successfully to alter the site-specificity of recombinases. Therefore, site-specific recombinases provide an attractive tool for the targeted modification of mammalian genomes. (C) 2005 Elsevier Inc. All rights reserved.

    Original languageEnglish
    Pages (from-to)431-469
    Number of pages39
    JournalBiotechnology Advances
    Issue number7-8
    Early online date31 May 2005
    Publication statusPublished - Nov 2005


    • genome engineering
    • transgenic animals
    • homologous recombination
    • gene targeting
    • recombinases
    • site-specific recombination
    • gene therapy
    • embryonic stem-cells
    • site-specific recombination
    • double-strand breaks
    • denoassociated virus vectors
    • mediated cassette exchange
    • triplex-forming oligonucleotides
    • germ-line transmission
    • nonviral genetic correction
    • beta-globin locus
    • mutant lox sites


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