Mice that make V
Genetically modified mice and methods for making an using them are provided, wherein the mice comprise a replacement of all or substantially all immunoglobulin heavy chain V gene segments, D gene segments, and J gene segments with at least one light chain V gene segment and at least one light chain J gene segment. Mice that make binding proteins that comprise a light chain variable domain operably linked to a heavy chain constant region are provided. Binding proteins that contain an immunoglobulin light chain variable domain, including a somatically hypermutated light chain variable domain, fused with a heavy chain constant region, are provided. Modified cells, embryos, and mice that encode sequences for making the binding proteins are provided.
1. A mouse whose germline genome comprises an endogenous immunoglobulin (Ig) heavy chain locus modified to comprise a human genomic germline kappa (κ) sequence comprising
(i) unrearranged functional human Ig light chain variable κ (hVκ) gene segments, and
(ii) all five unrearranged functional human Ig light chain joining κ (hJκ1-hJκ5) gene segments,
wherein the human genomic germline κ sequence
(A) replaces at the endogenous Ig heavy chain locus an endogenous genomic sequence comprising endogenous immunoglobulin heavy chain V gene segments, all endogenous immunoglobulin heavy chain D gene segments, and all endogenous immunoglobulin heavy chain J gene segments, and
(B) rearranges in a B cell during B cell development to form a rearranged Ig hVκ/hJκ gene sequence operably linked to the endogenous Ig C H nucleic acid sequence at the endogenous Ig heavy chain locus, and
wherein the mouse comprises a CD19 + B cell comprising the rearranged Ig hVκ/hJκ gene sequence operably linked to the endogenous Ig C H nucleic acid sequence.
2. The mouse of claim 1 , wherein the mouse is homozygous or heterozygous for the modified endogenous Ig heavy chain locus.
3. A mouse embryonic stem cell comprising an endogenous immunoglobulin (Ig) heavy chain locus modified to comprise a human genomic germline kappa (κ) sequence comprising
(i) unrearranged functional human Ig light chain variable κ (hVκ) gene segments, and
(ii) all five unrearranged functional human Ig light chain joining κ (hJκ1-hJκ5) gene segments,
wherein the human genomic germline κ sequence
(A) replaces at the endogenous Ig heavy chain locus an endogenous genomic sequence comprising endogenous immunoglobulin heavy chain V gene segments, all endogenous immunoglobulin heavy chain D gene segments, and all endogenous immunoglobulin heavy chain J gene segments, and
(B) rearranges in a B cell during B cell development to form a rearranged Ig Vκ/Jκ gene sequence operably linked to the endogenous Ig C H nucleic acid sequence at the endogenous Ig heavy chain locus.
4. A cell isolated from the mouse of claim 1 , wherein the cell is a CD19 + B cell comprising a rearranged Ig hVκ/hJκ nucleotide sequence operably linked to the endogenous Ig C H nucleic acid sequence at the endogenous mouse Ig heavy chain locus.
5. A hybridoma comprising a myeloma cell line fused with the CD19 + B cell of claim 4 .
6. A method for making a genetically modified mouse comprising:
(a) replacing in a mouse embryonic stem (ES) cell, at an endogenous immunoglobulin (Ig) heavy chain locus, an endogenous genomic sequence comprising endogenous immunoglobulin heavy chain V gene segments, all endogenous immunoglobulin heavy chain D gene segments, and all endogenous immunoglobulin heavy chain J gene segments with a human genomic germline kappa (κ) sequence comprising
(i) unrearranged functional human Ig light chain variable κ (hVκ) gene segments, and
(ii) all five unrearranged functional human Ig light chain joining κ (hJκ1-hJκ5) gene segments,
(b) introducing the mouse ES cell into a host mouse embryo to form a chimeric mouse embryo, and
(c) introducing the chimeric mouse embryo into a host mouse to develop into a genetically modified mouse.