Method for screening a test substance for activating a receptor associated with FGF 21 activity
Using betaKlotho or a substance that increases or inhibits betaKlotho activity as an agent for controlling the activity of FGF21 mediated by an FGF receptor, the present invention provides a pharmaceutical composition comprising such betaKlotho or such substance as an active ingredient, particularly, a pharmaceutical composition for anti-metabolic syndrome, and further particularly, a pharmaceutical composition for therapeutic or preventive use associated with the control of blood glucose level. In addition, the present invention provides a screening system for each of a substance that enhances or suppresses betaKlotho activity, an FGF21-like active substance, and a betaKlotho-like active substance, which uses a cell system that has expressed an FGF receptor and/or betaKlotho on the surface thereof.
1. A method for screening a test substance for activation of a receptor associated with FGF21 activity which comprises:
(a) introducing FGFR1c and FGFR3c genes and a betaKlotho gene into a cell that has endogenously expressed neither an FGF receptor nor betaKlotho, then allowing said test substance to act on a transformed cell expressing the FGFR1c or FGFR3c and the betaKlotho on the surface thereof and determining whether said test substance induced increased growth of said transformed cell or increased signalling activity in said transformed cell when compared with a transformed cell on which no test substance had acted;
(b) introducing an FGFR4 gene and a betaKlotho gene into a cell that has endogenously expressed neither an FGF receptor nor betaKlotho, then allowing said test substance to act on a transformed cell expressing the FGFR4 and the betaKlotho on the surface thereof and determining whether said test substance induced neither increased growth of said transformed cell nor increased signalling activity in said transformed cell when compared with a transformed cell on which no test substance had acted and
(c) introducing FGFR1c, FGFR2c or FGFR3c genes into a cell that has endogenously expressed neither an FGF receptor nor a betaKlotho then allowing said test substance to act on a transformed cell expressing the FGFR1c, FGFR2c or FGFR3c on the surface thereof and determining whether said test substance induced neither increased growth of said transformed cell nor increased signaling activity in said transformed cell as is the case with a transformed cell on which no test substance had acted;
whereby a positive showing in step (a) and a negative showing in steps (b) and (c) indicate activation of said receptor.