Screening method for SREBP pathway-specific inhibitors

Abstract

This invention provides a screening method for sterol regulatory element binding protein (SREBP) pathway-specific inhibitors using a mutant cultured cell, as well as therapeutic agents for hyperlipemia, arterial sclerosis, obesity or cancer containing an SREBP pathway-specific inhibitor selected by said screening method.

What is claimed is:  
     
         1 . The screening method for sterol regulatory element binding protein (SREBP) pathway specific inhibitors, which comprises using a cell in which a chimeric gene of a reporter gene and the gene encoding the C-terminus of SREBP has been expressed.  
     
     
         2 . The screening method of  claim 1 , which comprises the steps of: 
 (a) introducing a chimeric gene of a reporter gene and the gene encoding the C-terminus of SREBP into a cell in which SCAP has not lost response to sterols,    (b) culturing said cell in the presence of a test drug for SREBP pathway inhibitor to allow the cell to express said chimeric gene, and    (c) measuring any signal generated by said reporter gene.    
     
     
         3 . The screening method of  claim 1 , which comprises screening for SREBP pathway-specific inhibitors using a cell in which a chimeric gene of a reporter gene and the gene encoding the C-terminus of SREBP has been expressed, and then screening for sterol-like SREBP pathway-specific inhibitors using a cell in which SCAP has lost response to sterols and the same chimeric gene cell has been expressed.  
     
     
         4 . The screening method of  claim 3 , which comprises the steps of: 
 (a) introducing a chimeric gene of a reporter gene and the gene encoding the C-terminus of SREBP into a cell in which SCAP has not lost response to sterols,    (b) culturing the cell of step (a) in the presence of a test drug for sterol-like SREBP pathway inhibitor to allow the cell to express said chimeric gene,    (c) measuring any signal generated by said reporter gene,    (d) introducing the same chimeric gene as used in said step (a) into a cell in which SCAP has lost response to sterols,    (e) culturing the cell of step (d) in the presence of a test drug for sterol-like SREBP pathway inhibitor to allow the cell to express said chimeric gene,    (f) measuring any signal generated by said reporter gene, and    (g) comparing the signal measured in step (c) and the signal measured in step (f).    
     
     
         5 . The screening method of  claim 1 , which comprises screening for S2P-specific inhibitors using a cell in which a chimeric gene of a reporter gene and a gene encoding the stretch from the first transmembrane domain of SREBP to the cleavage site with SREBP Site 1 protease (S1P) has been expressed.  
     
     
         6 . The screening method of  claim 5 , which comprises the steps of: 
 (a) introducing a chimeric gene of a reporter gene and a gene encoding the stretch from the first transmembrane domain of SREBP to the cleavage site with SREBP Site 1 protease (S1P) into a cell which does not lack S2P,    (b) culturing said cell in the presence of a test drug for SREBP pathway inhibitor to express said chimeric gene, and    (c) measuring any signal generated by said reporter gene.    
     
     
         7 . The screening method of  claim 1 , wherein the reporter gene is green fluorescence protein gene carrying a nucleus localization signal (NLS) sequence.  
     
     
         8 . The screening method of  claim 1 , wherein the reporter gene is GAL4/VP16 fusion gene.  
     
     
         9 . The screening method of  claim 1 , wherein the mutant cultured cell is a mutant cultured cell derived from CHO cells.  
     
     
         10 . A vector obtained by inserting a chimeric gene of a reporter gene and the gene encoding the C-terminus of SREBP into a reporter gene expression vector.  
     
     
         11 . A vector obtained by inserting a chimeric gene of a reporter gene and a gene encoding the stretch from the first transmembrane domain of SREBP to the cleavage site with SREBP Site 1 protease (S1P) into a reporter gene expression vector.  
     
     
         12 . A SREBP pathway-specific inhibitor obtained by the screening method of  claim 8 .  
     
     
         13 . A therapeutic composition comprising the inhibitor of  claim 12.