FIGURE 9.

Insulin regulates FGFR4 mRNA and protein expression. A, primary cultures of mouse hepatocytes were treated with 100 nm insulin, total RNA or protein was prepared as described under “Experimental Procedures,” and specific mRNAs were analyzed by q-PCR and normalized to ribosomal protein L32 mRNA. FGFR4 protein levels were measured by immunoblotting with total protein extracts from control, insulin-treated, or insulin-treated plus wortmannin (W) or PIK 90 (P) as described under “Experimental Procedures.” The same blot was stripped and re-probed with an antibody against α-tubulin. B, mice were injected with streptozotocin (STZ) to induce Type I diabetes as described under “Experimental Procedures.” Serum glucose levels were 141.50 ± 13.89 mg/dl for the control (N) and 433.25 ± 16.47 mg/dl for the streptozotocin-treated groups (p < 0.0001). Total RNA was prepared, and expression of CYP7A1, FGFR4, and β-klotho mRNAs were analyzed by q-PCR and normalized to ribosomal protein L32 mRNA. *, p = 0.00002; **, p = 0.0001; ***, p = 0.0003; #, p = 0.00009.