Orphan Nuclear Receptor

Abstract

The present invention relates to a novel human orphan nuclear receptor that binds to a cytochrome P-450 monoxygenase (CYP) promoter and that is activated by compounds that induce CYP gene expression. The invention further relates to nucleic acid sequences encoding such a receptor, to methods of making the receptor and to methods of using the receptor and nucleic acid sequences encoding same. The invention also relates to non-human animals transformed to express the human receptor and to methods of using such animals to screen compounds for drug interactions and toxicities.

1 . An isolated human nuclear receptor that binds to a cytochrome P-450 monooxygenase promoter, or a DNA binding or ligand binding domain thereof.  
     
     
         2 . The receptor according to  claim 1  wherein the promoter is a cytochrome P-450 monooxygenase 3A4 (CYP3A4) promoter.  
     
     
         3 . The receptor according to  claim 2  wherein said receptor is hPXR.  
     
     
         4 . An isolated human nuclear receptor having the amino acid sequence given  FIG. 1 , or a fragment thereof, of at least 30 consecutive amino acids.  
     
     
         5 . A fusion protein comprising a DNA binding or ligand binding domain of hPXR and a non-hPXR-derived sequence.  
     
     
         6 . An isolated nucleic acid comprising a sequence encoding the receptor of  claim 1  or  4  or the fusion protein of  claim 5 .  
     
     
         7 . A construct comprising the nucleic acid of  claim 6  and a vector.  
     
     
         8 . A host cell comprising the construct of  claim 7 .  
     
     
         9 . A method of making the receptor of  claim 3 , or fragment thereof, comprising: 
 culturing a host cell containing an expression construct comprising a sequence encoding said receptor, or fragment thereof, operably linked to a promoter, under conditions such that said receptor, or fragment thereof, is produced, and    isolating said receptor, or fragment thereof.    
     
     
         10 . (canceled)  
     
     
         11 . A method of screening a test compound for its ability to activate or inhibit hPXR comprising: 
 i) preparing an expression vector comprising a sequence encoding a DNA binding domain and a hPXR ligand binding domain;    ii) preparing a reporter construct comprising a DNA binding site recognized by said DNA binding domain operably linked to a reporter gene,    iii) introducing said expression vector and said reporter construct into compatible host cells,    iv) incubating said cells resulting from step (iii) with said test compound, and    v) determining the level of expression of said reporter gene, 
 wherein enhancement of expression of said reporter gene in the presence of said test compound indicates that said test compound can activate hPXR, and  
 wherein inhibition of expression of said reporter gene in the presence of said test compound indicates that said test compound can inhibit hPXR.  
   
     
     
         12 - 24 . (canceled)