Method for screening agents for the treatment of diabetes

Abstract

A convenient screening tool and a convenient screening method for obtaining an agent for treating diabetes, a pharmaceutical composition for treating diabetes, and a process for manufacturing the pharmaceutical composition are disclosed. The screening tool is a G protein-coupled receptor, a variation functionally equivalent thereto, or a homologous polypeptide thereof which promotes insulin secretion under a high glucose concentration by activation, or cells transformed with an expression vector comprising a polynucleotide encoding the above polypeptide and expressing the polypeptide.

1 . A process for manufacturing a pharmaceutical composition for treating diabetes, comprising:
 bringing a cell which is transformed with an expression vector comprising at least one polynucleotide encoding at least one polypeptide and is expressing the at least one polypeptide, or a cell membrane thereof, into contact with an agent to be tested, wherein the at least one polypeptide is selected from:   (1) a polypeptide having the amino acid sequence of SEQ ID NO.: 2 or 16, or   (2) a polypeptide having an amino acid sequence in which 1 to 10 amino acids are deleted, substituted, and/or added in the amino acid sequence of SEQ ID NO.: 2 or 16, or having an amino acid sequence having a 90% or more homology with the amino acid sequence of SEQ ID NO.: 2 or 16, and exhibiting   (a) an activity of promoting insulin secretion from pancreatic β cells by activation under a high glucose concentration and/or   (b) an activity of increasing an amount of intracellular cAMP in the cells by activation;   analyzing whether or not the polypeptide is activated by the agent; and preparing a formulation containing the analyzed agent.   
     
     
         2 . The process according to  claim 1 , wherein the at least one polypeptide is a polypeptide comprising the amino acid sequence of SEQ ID NO.: 2 or 16, and exhibiting
 (a) an activity of promoting insulin secretion from pancreatic (β cells by activation under a high glucose concentration and/or   (b) an activity of increasing an amount of intracellular cAMP in the cells by activation.   
     
     
         3 . The process according to  claim 2 , wherein the pharmaceutical composition for treating diabetes is a pharmaceutical composition for promoting insulin secretion. 
     
     
         4 . A process for manufacturing a pharmaceutical composition for treating diabetes, comprising:
 bringing a cell which is transformed with an expression vector comprising at least one polynucleotide encoding at least one polypeptide and is expressing the at least one polypeptide, a cell membrane thereof, or the at least one polypeptide, into contact with an agent to be tested, in the presence of a labeled agonist of the at least one polypeptide, the at least one polypeptide being   (1) a polypeptide having the amino acid sequence of SEQ ID NO.: 2 or 16, or   (2) a polypeptide having an amino acid sequence in which 1 to 10 amino acids are deleted, substituted, and/or added in the amino acid sequence of SEQ ID NO.: 2 or 16, or having an amino acid sequence having a 90% or more homology with the amino acid sequence of SEQ ID NO.: 2 or 16, and exhibiting   (a) an activity of promoting insulin secretion from pancreatic β cells by activation under a high glucose concentration and/or   (b) an activity of increasing an amount of intracellular cAMP in the cells by activation;   analyzing a change of an amount of the labeled agonist which binds to the cell, the cell membrane thereof, or the at least one polypeptide; and preparing a pharmaceutical composition containing the analyzed agent.   
     
     
         5 . The process according to  claim 4 , wherein the at least one polypeptide is at least one polypeptide comprising the amino acid sequence of SEQ ID NO.: 2 or 16, and exhibiting
 (a) an activity of promoting insulin secretion from pancreatic β cells by activation under a high glucose concentration and/or   (b) an activity of increasing an amount of intracellular cAMP in the cells by activation.   
     
     
         6 . The process according to  claim 4 , wherein the pharmaceutical composition for treating diabetes is a pharmaceutical composition for promoting insulin secretion. 
     
     
         7 . A method for treating diabetes, comprising administering to a subject in need thereof an agent that activates
 (1) a polypeptide having the amino acid sequence of SEQ ID NO.: 2 or 16, or
 (2) a polypeptide having an amino acid sequence in which 1 to 10 amino acids are deleted, substituted, and/or added in the amino acid sequence of SEQ ID NO.: 2 or 16, or having an amino acid sequence having a 90% or more homology with the amino acid sequence of SEQ ID NO.: 2 or 16, and exhibiting 
 (a) an activity of promoting insulin secretion from pancreatic β cells by activation under a high glucose concentration and/or 
 (b) an activity of increasing an amount of intracellular cAMP in the cells by activation; 
   in an effective amount thereof.   
     
     
         8 . The method according to  claim 7 , wherein the polypeptide is a polypeptide comprising the amino acid sequence of SEQ ID NO.: 2 or 16, and exhibiting
 an activity of promoting insulin secretion from pancreatic β cells by activation under a high glucose concentration and/or   an activity of increasing an amount of intracellular cAMP in the cells by activation.   
     
     
         9 . A method for promoting insulin secretion, comprising administering to a subject in need thereof an agent that activates
 a polypeptide having the amino acid sequence of SEQ ID NO.: 2 or 16, or   a polypeptide having an amino acid sequence in which 1 to 10 amino acids are deleted, substituted, and/or added in the amino acid sequence of SEQ ID NO.: 2 or 16, or having an amino acid sequence having a 90% or more homology with the amino acid sequence of SEQ ID NO.: 2 or 16, and exhibiting   an activity of promoting insulin secretion from pancreatic β cells   by activation under a high glucose concentration and/or   an activity of increasing an amount of intracellular cAMP in the cells by activation;   in an effective amount thereof.   
     
     
         10 . The method according to  claim 9 , wherein the polypeptide is a polypeptide comprising the amino acid sequence of SEQ ID NO.: 2 or 16, and exhibiting
 (a) an activity of promoting insulin secretion from pancreatic β cells by activation under a high glucose concentration and/or   (b) an activity of increasing an amount of intracellular cAMP in the cells by activation.