Methods for identifying compounds for regulating muscle mass or function using vasoactive intestinal peptide receptors

Abstract

Screening methods for identifying compounds that regulate skeletal muscle atrophy or hypertrophy, regulate the activity or expression of the vasoactive intestinal peptide receptors (VPAC) or regulate expression of vasoactive intestinal peptide (VIP) or VIP analogs are provided. Methods for the prophylactic or therapeutic treatment of skeletal muscle atrophy utilizing VPAC as the target for intervention are described.

What is claimed is:  
     
         1 . A method for identifying candidate compounds for regulating skeletal muscle mass or function, comprising: 
 a. contacting a test compound with a VPAC receptor;    b. determining whether the test compound binds to the VPAC receptor; and    c. identifying those test compounds that bind VPAC receptor as candidate compounds for regulating skeletal muscle mass or function.    
     
     
         2 . A method for identifying candidate compounds for regulating skeletal muscle mass or function, comprising: 
 a. contacting a test compound with a VPAC receptor;    b. determining whether the test compound binds to the VPAC receptor;    c. selecting the compounds that bind the VPAC receptor and further determining whether the test compound modulates muscle mass or function in a skeletal muscle atrophy model system; and    d. identifying those test compounds that modulate muscle mass or function in a skeletal muscle atrophy model system as candidate compounds for regulating skeletal muscle mass or function.    
     
     
         3 . The method according to  claim 1 , wherein: in the step (a) the VPAC receptor is expressed on a cell surface, and binding of the test compound to the VPAC receptor activates the VPAC receptor.  
     
     
         4 . The method according to  claim 1 , further comprising: administering the test compound determined to bind to the VPAC receptor, to a non-human animal, and determining whether the test compound regulates skeletal muscle mass or function in the animal, wherein test compounds that regulate skeletal muscle mass or function in the animal are identified as candidate compounds for regulating skeletal muscle mass or function in vivo.  
     
     
         5 . The method for identifying candidate compounds according to  claim 1 , wherein the VPAC receptor is a VPAC 1  receptor, and has an amino acid sequence greater than about 80% identical to SEQ ID NO: 1.  
     
     
         6 . The method for identifying candidate compounds according to  claim 5 , wherein the VPAC receptor is a VPAC 1  receptor, and has an amino acid sequence greater than about 90% identical to SEQ ID NO: 1.  
     
     
         7 . The method for identifying candidate compounds according to  claim 1 , wherein the VPAC receptor is a VPAC 1  receptor, and has an amino acid sequence greater than about 80% identical to SEQ ID NO: 2.  
     
     
         8 . The method for identifying candidate compounds according to  claim 7 , wherein the VPAC receptor is a VPAC 1  receptor, and has an amino acid sequence greater than about 90% identical to SEQ ID NO: 2.  
     
     
         9 . The method for identifying candidate compounds according to  claim 1 , wherein the VPAC receptor is a VPAC 1  receptor, and is selected from the group consisting of SEQ ID NOs: 1, 2, 3, 4, 5, 6, 7, 8, and 9.  
     
     
         10 . The method for identifying candidate compounds according to  claim 1 , wherein the VPAC receptor is a VPAC 2  receptor, and has an amino acid sequence greater than about 80% identical to SEQ ID NO: 10.  
     
     
         11 . The method for identifying candidate compounds according to  claim 10 , wherein the VPAC receptor is a VPAC 2  receptor, and has an amino acid sequence greater than about 90% identical to SEQ ID NO: 10.  
     
     
         12 . The method for identifying candidate compounds according to  claim 1 , wherein the VPC receptor is a VPAC 2  receptor, and has an amino acid sequence greater than about 80% identical to SEQ ID NO: 11.  
     
     
         13 . The method for identifying candidate compounds according to  claim 12 , wherein the VPAC receptor is a VPAC 2  receptor, and has an amino acid sequence greater than about 90% identical to SEQ ID NO: 11.  
     
     
         14 . The method for identifying candidate compounds according to  claim 1 , wherein the VPAC receptor is a VPAC 2  receptor, and has an amino acid sequence greater than about 80% identical to SEQ ID NO: 12.  
     
     
         15 . The method for identifying candidate compounds according to  claim 14 , wherein the VPAC receptor is a VPAC 2  receptor, and has an amino acid sequence greater than about 90% identical to SEQ ID NO: 12.  
     
     
         16 . The method for identifying candidate compounds according to  claim 1 , wherein the VPAC receptor is a VPAC 2  receptor, and is selected from the group consisting of SEQ ID NOs: 10, 11, 12, 13, 14, 15, and 16.  
     
     
         17 . The method for identifying candidate compounds according to  claim 3 , wherein the VPAC receptor is expressed on a eukaryotic cell.  
     
     
         18 . The method for identifying candidate compounds according to  claim 17 , wherein determining whether the test compound activates the VPAC receptor involves determining cellular cAMP level.  
     
     
         19 . The method for identifying candidate compounds according to  claim 18 , wherein the cell further comprises a reporter gene operatively associated with a cAMP responsive element and measuring the cellular cAMP level involves measuring expression or activity of the reporter gene.  
     
     
         20 . A method for identifying candidate compounds for regulating skeletal muscle mass or function comprising: 
 a. contacting a test compound with a cell expressing a functional VPAC 2  receptor, and determining level of activation of VPAC 2  receptor resulting from the interaction of the test compound with VPAC 2  receptor;    b. contacting the test compound with a cell expressing a functional VPAC 1  receptor, and determining level of activation of VPAC 1  receptor resulting from the interaction of the test compound with VPAC 1  receptor;    c. comparing the level of VPAC 2  receptor activation with the level of VPAC 1  receptor activation; and    d. identifying those test compounds that selectively activate VPAC 2  receptor over the VPAC 1  receptor as candidate compounds for regulating skeletal muscle mass or function.    
     
     
         21 . The method for identifying candidate compounds for regulating skeletal muscle mass or function according to  claim 20 , further comprising: selecting the compound that selectively activated VPAC 2  receptor over VPAC 1  receptor according to  claim 20 , and further determining whether the test compound modulates muscle mass or function in a skeletal muscle atrophy model system; and identifying those compounds that modulate muscle mass or function in a skeletal muscle atrophy model system as candidate compounds for regulating skeletal muscle mass or function.  
     
     
         22 . The method according to  claim 20  wherein the candidate compound exhibits about 100-fold or greater selectivity for VPAC 2  receptor.  
     
     
         23 . The method according to  claim 20  wherein the candidate compound exhibits about 1000-fold or greater selectivity for VPAC 2  receptor.  
     
     
         24 . The method according to  claim 20  wherein the candidate compound exhibits between about 1-fold and about 100-fold selectivity for VPAC 2  receptor.