Compounds that selectively bind to expanded polyglutamine repeat domains and methods of use thereof

Abstract

Compounds that selectively bind to expanded polyglutamine repeats are disclosed. Such compounds are characterized in that they bind to a first polyglutamine peptide consisting of 60 glutamine residues under conditions in which they do not bind to a second polyglutamine peptide consisting of 20 glutamine residues. Conjugates of such compounds, nucleic acids encoding the same, and methods of use thereof are also disclosed.

That which is claimed is:  
     
         1 . A compound according to Formula I:  
       X 1 —R 11 R 12 R 13 R 14 —Y 1   (I)  
       wherein: 
 R 11  is Trp;  
 R 12  is (i) Trp or (ii) a charged amino acid selected from the group consisting of Lys, Arg and His;  
 R 13  is (i) Trp or (ii) a charged amino acid selected from the group consisting of Lys, Arg and His;  
 subject to the proviso that one of R 12  and R 13  is Trp and the other is a charged amino acid;  
 R 14  is Trp;  
 X 1  is a peptide consisting of from 1 to 10 amino acids, or is deleted; and  
 Y 1  is a peptide consisting of from 1 to 10 amino acids, or is deleted;  
 or a physiologically acceptable salt thereof.  
 
     
     
         2 . A compound according to  claim 1  selected from the group consisting of:  
       
         
           
                 
                 
                 
                 
               
                     
                     
                 
                     
                   WKWW; 
                   (SEQ ID NO:1) 
                     
                 
                     
                     
                 
                     
                   WWKW; 
                   (SEQ ID NO:2) 
                 
                     
                     
                 
                     
                   SNWKWWPGIFD (QBP1); 
                   (SEQ ID NO:3) 
                 
                     
                     
                 
                     
                   SNWKWWPGIFDSNWKWWPGIFD; and 
                   (SEQ ID NO:4) 
                 
                     
                     
                 
                     
                   WKWWWKWW. 
                   (SEQ ID NO:5) 
                 
                     
                     
                 
             
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
       
     
     
         3 . A compound according to  claim 1  conjugated to a detectable group.  
     
     
         4 . A compound according to  claim 1  conjugated to a heterologous protein or peptide.  
     
     
         5 . A compound according to  claim 1  conjugated to a fluorescent group.  
     
     
         6 . A compound according to  claim 1  conjugated to an enzyme.  
     
     
         7 . A compound according to  claim 1  conjugated to thioredoxin.  
     
     
         8 . A nucleic acid encoding a compound according to  claim 1 .  
     
     
         9 . A nucleic acid according to  claim 8 , wherein said nucleic acid is a DNA.  
     
     
         10 . A nucleic acid construct comprising a nucleic acid according to  claim 7  operatively associated with a promoter.  
     
     
         11 . A transfer vector comprising a construct according to  claim 10 .  
     
     
         12 . A transfer vector according to  claim 11 , wherein said transfer vector is a viral vector.  
     
     
         13 . A cell that contains and expresses a nucleic acid according to  claim 8 .  
     
     
         14 . A method of treating a cell that contains and expresses a protein having an expanded polyglutamine region, said method comprising administering to said cell a treatment effective amount of a compound according to  claim 1 .  
     
     
         15 . A method according to  claim 14 , wherein said protein is selected from the group consisting of huntingtin, atrophin 1, ataxin 1, ataxin 2, ataxin 6, ataxin 7, and androgen receptor protein.  
     
     
         16 . A method according to  claim 15 , wherein said compound is administered directly to said cell.  
     
     
         17 . A method according to  claim 15 , wherein said compound is administered to said cell by administering a vector that contains a nucleic acid construct that expresses said compound in said cell.  
     
     
         18 . A method of treating a subject afflicted with a neurodegenerative disease characterized by the presence of expanded polyglutamine repeats, said method comprising administering to said subject a treatment effective amount of a compound according to  claim 1 .  
     
     
         19 . A method according to  claim 18 , wherein said disease is selected from the group consisting of Huntington's disease, dentatorubral pallidoluysian atrophy, spinobulbar muscular atrophy, and spinocerebellar ataxia types 1, 2, 3, 6 and 7.  
     
     
         20 . A method according to  claim 18 , wherein said compound is administered directly to said cell.  
     
     
         21 . A method according to  claim 18 , wherein said compound is administered to said cell by administering a vector that contains a nucleic acid construct that expresses said compound in said cell.  
     
     
         22 . A method of detecting an expanded polyglutamine domain in a sample suspected of containing the same, said expanded polyglutamine domain consisting of at least 40 glutamine residues, said method comprising the steps of: 
 (a) contacting a sample with a compound according to  claim 1;  and then    (b) determining whether the compound binds with the sample, the presence of binding indicating the presence of an expanded polyglutamine domain in said sample.    
     
     
         23 . A method according to  claim 22 , wherein said compound is conjugated to a detectable group, and wherein said detecting step is carried out by determining the presence or absence of binding of said detectable group to said sample.  
     
     
         24 . A method according to  claim 22 , wherein said compound is conjugated to thioredoxin, and said detecting step is carried out by turbidometric assay.  
     
     
         25 . A method according to  claim 22 , wherein said sample comprises a protein.  
     
     
         26 . A method according to  claim 22 , wherein said sample comprises a protein collected from a patient.  
     
     
         27 . A method according to  claim 22 , wherein said protein is selected from the group consisting of huntingtin, atrophin 1, ataxin 1, ataxin 2, ataxin 6, ataxin 7, and androgen receptor protein.  
     
     
         28 . A method of screening compounds for activity in treating a neurodegenerative disease characterized by the presence of expanded polyglutamine repeats, said method comprising: 
 (a) providing a reagent system comprising: (i) a first compound comprising an expanded polyglutamine segment conjugated to a first signal group and (ii) a second compound comprising an expanded polyglutamine segment conjugated to a second signal group, wherein said first and second signal groups generate a detectable event when conjugated together, and wherein each of said expanded polyglutamine segments consists of at least 40 polyglutamine residues;    (b) combining said test compound with said reagent system; and then    (c) determining the presence or absence of said detectable event, the absence of said detectable event indicating that said test compound is a candidate for activity in treating an expanded polyglutamine repeat disease.    
     
     
         29 . A method according to  claim 28 , wherein said detectable event is the emission of a signal or the quenching of a signal.  
     
     
         30 . A method according to  claim 28 , wherein said first and second signal groups are fluorescent groups that are members of a fluorescence resonance energy transfer (FRET) pair, 
 determining the presence or absence of fluorescence resonance energy transfer between said first and second fluorescent groups; the absence of fluorescence resonance energy transfer indicating that said compound is a candidate for activity in treating an expanded polyglutamine repeat disease.    
     
     
         31 . A method according to  claim 30 , wherein said first fluorescent group is cyan fluorescent protein and said second fluorescent group is yellow fluorescent protein.  
     
     
         32 . A method according to  claim 30 , wherein said test compound is a member of a combinatorial library.  
     
     
         33 . A method according to  claim 30 , wherein said reagent system is an in vitro system, and said combining step is carried out by adding said test compound to said in vitro system  
     
     
         34 . A method according to  claim 30 , wherein said reagent system is an in vivo cell system, and said combining step is carried out by adding said test compound to said in vivo cell system.  
     
     
         35 . A method of screening compounds for activity in treating an expanded polyglutamine repeat disease, comprising: 
 (a) providing a reagent system comprising an expanded polyglutamine segment conjugated to thioredoxin;    (b) combining the test compound with the reagent system; and then    (c) determining the presence or absence of aggregation in the reagent system, the absence of aggregation indicating that the compound is a candidate for activity in treating an expanded polyglutamine repeat disease.    
     
     
         36 . A method according to  claim 35 , wherein said detecting step is carried out by turbidometric assay.  
     
     
         37 . A method according to  claim 35 , wherein said test compound is a member of a combinatorial library.  
     
     
         38 . A method according to  claim 35 , wherein said reagent system is an in vitro system, and said combining step is carried out by adding said test compound to said in vitro system  
     
     
         39 . A method according to  claim 35 , wherein said reagent system is an in vivo cell system, and said combining step is carried out by adding said test compound to said in vivo cell system.