Fig 1: PTP4A1 regulates the expression of FGF21 via the activation of transcription factor CREBH. (A) The mRNA levels of Fgf21 in the liver of wild-type (WT) and Ptp4a1-/- mice fed an HF diet for 12 weeks (n = 6). (B) Plasma FGF21 levels in WT and Ptp4a1-/- mice fed an HF diet for 12 weeks (n = 6). (C) The mRNA levels of FGF21 and PTP4A1 in Hep3B infected by adenovirus (Ad)-Control (Ctrl) or Ad-PTP4A1 (n = 6). (D) The mRNA levels of FGF21 and PTP4A1 in Hep3B infected by lentivirus expressing-shPTP4A1 or -scramble control (n = 6). (E) Co-immunoprecipitation assay in HEK 293T transfected by HA-Mock, HA-CREBH(N), or HA-CREBH(F) with Flag-Mock, Flag-PTP4A1, or Flag-mutant PTP4A1 (D74A/C104S). Flag antibody was used for immunoprecipitation. Data represent three independent experiments. (F) FGF21-luciferase reporter assay in HEK293T transfected by Mock, CREBH(N), PTP4A1, mutant PTP4A1, CREBH(N)+PTP4A1, or CREBH(N)+mutant PTP4A1. (G) Western blot analysis for the CREBH(N) in the nuclear fraction of liver from WT and Ptp4a1-/- mice fed an HF diet. Lamin B1 was used for loading control. The quantification graph is presented on the right (n = 3). (H) Chromatin immunoprecipitation assay (n = 4). The FGF21 gene was amplified by specific primers after immunoprecipitation by an anti-HA antibody in mock-, HA-CREBH-, PTP4A1-, or HA-CREBH+PTP4A1-treated Hep3B. GAPDH was used as an internal control after immunoprecipitation by an anti-RNA polymerase II antibody. Data represent three independent experiments. Data are presented as the mean ± standard error of the mean. **P < 0.01 (two‐tailed Student's t‐test for A, C, D, and G; Mann-Whitney U test for B; two-way ANOVA for F; one-way ANOVA for H).