Genetically modified mouse with an inducible ACVR1 gene with a mutant R206H exon 5 that has ectopic bone formation

Abstract

A genetically modified mouse is provided that comprises a conditional Acvr1 allele that comprises a mutated exon that, upon induction, converts to a mutant exon phenotype, wherein the mutant exon phenotype includes ectopic bone formation. Mice comprising a mutant Acvr1 exon 5 in antisense orientation, flanked by site-specific recombinase recognition sites, are provided, wherein the mice further comprise a site-specific recombinase that recognizes the site-specific recombinase recognitions sites, wherein the recombinase is induced upon exposure of the mouse to tamoxifen. Upon exposure to tamoxifen, the recombinase is expressed and acts on the RRS-flanked mutant exon 5 and places the mutant exon 5 in sense orientation and deletes the wild-type exon.

We claim: 
     
       1. A genetically modified mouse whose genome comprises a modified mouse Activin A receptor type 1 (Acvr1) gene comprising:
 i) a human Acvr1 gene exon 5of the Acvr1 gene, encoding glutamic acid at the first codon instead of aspartic acid, in sense orientation flanked upstream and downstream by first pair of recombination recognition sites; and 
 ii) a mutant exon 5 of a mouse Acvr1 genecomprising an R206H mutation, in antisense orientation and encoding an R206H variation, flanked upstream and downstream by second pair of recombination recognition sites that are different than the first pair of recombination recognition sites; 
 wherein the first and second recombination recognition sites are oriented so that a recombinase can invert the mutant exon 5 into sense orientation, orientation and delete the human exon 5, and allow thereby producing a mutant Acvr1 gene comprising the mutant an exon 5 encoding the R206H variation, and allowing the mutant Acvr1 gene to be expressed resulting in ectopic bone formation. 
 
     
     
       2. A transgenic genetically modified mouse derived from the mouse of  claim 1 , wherein said transgenic the genetically modified mouse so derived has a genome comprising a nucleic acid sequence encoding the mutant the modified mouse Acvr1 comprising the mutant exon 5, and wherein the mouse expresses the mutant Acvr1 comprising the mutant exon 5 resulting in ectopic bone formation gene. 
     
     
       3. The genetically modified mouse of  claim 2 , wherein the first and second pairs of recombination recognition sites are Lox2372 and LoxP or vice versa. 
     
     
       4. The genetically modified mouse of  claim 2 , wherein the recombinase is a tamoxifen-inducible CreER T2 . 
     
     
       5. The genetically modified mouse of claim 1, wherein the mouse further comprises a gene encoding an inducible recombinase.  
     
     
       6. The genetically modified mouse of claim 5, wherein the inducible recombinase comprises inducible Cre recombinase.  
     
     
       7. The genetically modified mouse of claim 6, wherein the inducible Cre recombinase comprises tamoxifen-inducible Cre-ER T  or Cre-ER T2  recombinase.  
     
     
       8. The genetically modified mouse of claim 5, wherein the inducible recombinase is expressed in a cell in the mouse comprising the modified mouse Acvr1 gene.  
     
     
       9. The genetically modified mouse of claim 6, wherein the inducible recombinase is expressed in a cell in the mouse comprising the modified mouse Acvr1 gene.  
     
     
       10. The genetically modified mouse of claim 7 wherein the inducible recombinase is expressed in a cell in the mouse comprising the modified mouse Acvr1 gene.  
     
     
       11. The genetically modified mouse of claim 5, wherein the gene encoding an inducible recombinase is at the ROSA26 locus.  
     
     
       12. The genetically modified mouse of claim 1, wherein the mouse is heterozygous for the modified mouse Acvr1 gene.  
     
     
       13. The genetically modified mouse of claim 1, wherein the mouse is homozygous for the modified mouse Acvr1 gene.  
     
     
       14. The genetically modified mouse of claim 2, wherein the genetically modified mouse has a genome comprising a nucleic acid sequence encoding the mutant Acvr1 gene, and wherein the mouse expresses the mutant Acvr1 gene resulting in ectopic bone formation.  
     
     
       15. The genetically modified mouse of claim 14, wherein the recombinase is an inducible Cre recombinase.  
     
     
       16. The genetically modified mouse of claim 15, wherein the inducible Cre recombinase is tamoxifen-inducible Cre-ER T  or tamoxifen-inducible Cre-ER T2  recombinase.  
     
     
       17. The genetically modified mouse of claim 2, wherein the genetically modified mouse has ectopic bone formation.