ACC2-knockout mice and uses thereof

Abstract

The present invention discloses transgenic mice with inactivating mutations in the endogenous gene for the acetyl-CoA carboxylase-2 isoform of acetyl-CoA carboxylase. Inactivation of acetyl-CoA carboxylase-2 results in mice exhibiting a phenotype of reduced malonyl-CoA levels in skeletal muscle and heart, unrestricted fat oxidation, and reduced fat accumulation in the liver and fat storage cells. As a result, the mice consume more food but accumulate less fat and remain leaner than wild type mice fed the same diet. These results demonstrate that inhibition of ACC2 acetyl-CoA carboxylase could be used to regulate fat oxidation and accumulation for purposes of weight control. The transgenic mice of the instant invention provide a useful animal model to identify such inhibitors and for studying the mechanisms of fat metabolism and weight control.

What is claimed is:  
     
         1 . A transgenic mouse, said mouse comprising a mutation in an endogenous ACC2 gene for the acetyl-CoA carboxylase-2 isoform of acetyl-CoA carboxylase, wherein said mutation inactivates said gene and results in the lack of expression of a functional acetyl-CoA carboxylase-2 isoform.  
     
     
         2 . The mouse of  claim 1  wherein one or more exons of said ACC2 gene has been deleted.  
     
     
         3 . The mouse of  claim 2 , wherein said exons have been replaced with heterologous DNA sequences.  
     
     
         4 . The mouse of  claim 3 , wherein said heterologous DNA sequences comprise an HPRT expression cassette.  
     
     
         5 . The mouse of  claim 4 , wherein an exon encoding a biotin binding motif, of ACC2 is replaced with an HPRT expression cassette.  
     
     
         6 . The mouse of  claim 1 , wherein said mouse exhibits a phenotype comprising a metabolic reduction in malonyl-CoA production in skeletal muscle and heart.  
     
     
         7 . The mouse of  claim 6 , further comprising a phenotype of unrestricted fat oxidation and reduced fat accumulation in the liver and fat storage cells.  
     
     
         8 . The mouse of  claim 7 , further comprising a phenotype of consuming more calories than a wild type mouse yet accumulating less fat than a wild type mouse.  
     
     
         9 . A method of screening for an inhibitor of acetyl-CoA carboxylase-2 isoform activity comprising the steps of: 
 administering potential inhibitors to wild type mice; and,    screening for mice which exhibit the phenotype of the transgenic mouse of  claim 8 .    
     
     
         10 . An acetyl-CoA carboxylase-2 inhibitor identified by the method of  claim 9 .  
     
     
         11 . A pharmaceutical composition comprising the acetyl-CoA carboxylase-2 inhibitor of  claim 10  and a pharmaceutically acceptable carrier.  
     
     
         12 . A method of inhibiting fat accumulation and promoting fatty acid oxidation to promote weight loss or maintenance in said individual comprising the step of administering a pharmaceutical composition comprising an acetyl-CoA carboxylase-2 inhibitor of  claim 10  and a pharmaceutically acceptable carrier to, said individual.  
     
     
         13 . A method of obtaining a purified preparation of acetyl-CoA carboxylase-1 protein which is free of acetyl-CoA carboxylase-2 comprising the step of: 
 purifying said acetyl-CoA carboxylase-1 protein from tissues obtained from the transgenic mouse of  claim 1 .    
     
     
         14 . A method of obtaining murine antibodies against acetyl-CoA carboxylase-2 which are less crossreactive with acetyl-CoA carboxylase-1 and other mouse proteins comprising the step of: 
 generating said antibodies in the transgenic mouse of  claim 1 .    
     
     
         15 . A cell line derived from the transgenic mouse of  claim 1 .  
     
     
         16 . The cell line of  claim 15 , wherein said cell line is derived from cells selected from the group consisting of muscle cells, heart cells, adipose cells, and liver cells.  
     
     
         17 . A method of screening for agonists and antagonists of ACC2 comprising the steps of: 
 administering a candidate compound to the cell line of  claim 15  and to cell lines derived from wild type mice; and,    monitoring said cell lines for alterations in cellular activity, wherein a compound that specifically acts on ACC2 will have alter cellular activity in wild type cells but will have no effects on the cell line of  claim 15 .    
     
     
         18 . The method of  claim 17 , wherein monitored cellular activities are selected from the group consisting of mRNA expression, protein expression, protein secretion, and lipid metabolism.