Massachusetts Institute of Technology

Albert Einstein College of Medicine

Eric Bouhassira

Philippe Leboulch

Karen Westerman

Philippe LeBoulch

Ken Julian Takekoshi

Methods and compositions for transforming cells, resulting in efficient and stable site-specific integration of transgenes, are disclosed. Transformation is achieved by providing an acceptor DNA containing two inverted lox sequences and a donor DNA containing the same two inverted lox sequences, and then contacting the acceptor and donor DNA with a recombinase (e.g., Cre or Flp) which causes recombination at the lox sequences contained in the DNAs. Prior to recombination, the acceptor DNA is preferably integrated into the genome of a cell, such as an embryonic stem cell or a fertilized egg. The acceptor DNA optionally may further contain a negatively selectable marker to allow for screening of cells which have undergone the desired site-specific recombination (e.g., DNA cassette exchange).

Methods and compositions for transforming cells

Methods and compositions for transforming cells, resulting in efficient and stable site-specific integration of transgenes, are disclosed. Transformation is achieved by introducing into a cell an acceptor vector, preferably a retroviral vector, which integrates into the genome of the cell. The acceptor vector comprises two incompatible lox sequences, L1 and L2. A donor vector is then introduced into the cell comprising a transgene flanked by the same L1 and L2 sequences. Stable gene transfer is initiated by contacting the lox L1 and L2 sequences with Cre recombinase.

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Hastings on Hudson, NY, United States of America

Eric Bouhassira