Endocrine cell lines and method of using the same
In accordance with the present invention, there are provided (1) various cell lines derived from hypothalamus and Langerhans islets of mammals, (2) process for producing an active peptide and expression cloning system of active peptide precursor gene using the cell line as a host, (3) a method of screening or evaluating a substance capable of acting on the cells using the cell line, (4) a method of screening or isolating a useful gene or useful peptide using the cell line and (5) a highly-sensitive and simple assay system for GPCR ligand used in the above expression cloning system.
1 . A method of isolating a DNA encoding a peptide capable of acting as an agonist, antagonist or inverse agonist for an aimed receptor, which comprises the following steps (1) to (5):
(1) transfecting a cDNA or a DNA derived from a chromosome into a cell line derived from an endocrine cell to obtain a transformant;
(2) culturing the transformant of the above (1) to express the transfected DNA and contacting a culture supernatant, a cell extract or a membrane fraction of the transformant or the transformant per se with a cell where the aimed receptor is expressed;
(3) detecting a response reaction of the cell on the basis of the receptor;
(4) selecting a transformant where the culture supernatant, the cell extract or the membrane fraction of the transformant or the transformant per se shows the aimed activity; and
(5) identifying the DNA transfected in the transformant of the above (4) as a DNA for giving the aimed activity to the transformant.
2 - 108 . (canceled)