Fig. 2.

Overexpression of Klotho protein increased glucose-induced insulin secretion in MIN6 cells. MIN6 cells were transfected with pAAV-mKL or vehicles (transfection agent alone) for 72 h. A, Western blot analysis of Klotho protein expression. B, Quantification of full-length Klotho protein expression. C, Quantification of short-form Klotho protein expression. Results were standardized to β-actin and then expressed as fold changes vs. the control group (transfection reagent alone). Data are means ± sem (n = 4 independent experiments). **, P < 0.01, ***, P < 0.001 vs. the control group; ++, P < 0.01, +++, P < 0.001 vs. the pAAV-GFP group. D, Insulin secretion from MIN6 cells was determined by measuring insulin levels in the medium. Transfected cells were incubated in serum-free DMEM for 2 h before challenged with glucose at 2.8, 7.0, and 16.7 mm in KRB solution for 1 h (see Materials and Methods). Data are means ± sem (n = 4 independent experiments). **, P < 0.01, ***, P < 0.001 vs. control group (transfection reagent alone) at the glucose concentration of 2.8 mm; ++, P < 0.01, +++, P < 0.001 vs. the pAAV-GFP group at the glucose concentration of 7.0 or 16.7 mm; ^^^, P < 0.001 vs. the pAAV-mKL group at the glucose concentration of 7.0 mm.