Methods and compositions for the targeted modification of a mouse embryonic stem cell genome

#The official copy of the sequence listing is submitted electronically via EFS-Web as an ASCII formatted sequence listing with a file named 487024SEQLIST.TXT, created on Nov. 13, 2016, and having a size of 27.6 kilobytes, and is filed concurrently with the specification. The sequence listing contained in this ASCII formatted document is part of the specification and is herein incorporated by reference in its entirety.

#While rats have been regarded as an important animal model system that can recapitulate the pathology of various human diseases, including, but not limited to, cardiovascular (e.g., hypertension), metabolic (e.g., obesity, diabetes), neurological (e.g., pain pathologies), and a variety of cancers, the use of rats in modeling human diseases has been limited as compared to mice, due in part to unavailability of germline-transmittable pluripotent rat cells, which can sustain their pluripotency following a series of genetic modifications in vitro, e.g., one or more serial electroporations, and due in part to lack of efficient targeting technologies that allow introduction or deletion of large genomic DNA sequences, or replacement of large endogenous genomic DNA sequences with exogenous nucleic acid sequences in pluripotent rat cells.

#There is a need in the art for compositions and methods that allow precise targeted changes in the genome of an organism, which can open or expand current areas of target discovery and validate therapeutic agents more quickly and easily.

#The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

#FIG. 1 depicts rat ESCs, which grow as compact spherical colonies that routinely detach and float in the dish.

#FIG. 2A through D depict various pluripotency markers expressed by rat ESCs: A depicts Oct-4 (green); B depicts Sox-2 (red); C depicts DAPI (blue); D depicts an overlay of pluripotency markers expressed by rESCs.

#Compositions and methods are provided for modifying a rat, eukaryotic, non-rat eukaryotic, mammalian, non-human mammalian, human, rodent, non-rat rodent, mouse, or hamster genomic locus of interest via bacterial homologous recombination (BHR) in a prokaryotic cell. Compositions and methods are also provided for genetically modifying a genomic locus of interest, for example, rat, eukaryotic, non-rat eukaryotic, mammalian, non-human mammalian, human, rodent, non-rat rodent, or mouse genomic locus of interest using a large targeting vector (LTVEC) in combination with endonucleases. Compositions and methods are also provided for producing a genetically modified non-human animal, for example, a rat, mouse, rodent, or non-rat rodent, comprising one or more targeted genetic modifications. Also provided are isolated human and non-human totipotent or pluripotent stem cells, in particular rat embryonic stem cells, that are capable of sustaining pluripotency following one or more serial genetic modifications in vitro, and that are capable of transmitting the targeted genetic modifications to subsequent generations through germline.

#Glossary

#The term “embryonic stem cell” or “ES cell” as used herein includes an embryo-derived totipotent or pluripotent cell that is capable of contributing to any tissue of the developing embryo upon introduction into an embryo. The term “pluripotent cell” as used herein includes an undifferentiated cell that possesses the ability to develop into more than one differentiated cell types. The term “non-pluripotent cell” includes cells that are not pluripotent cells.