Figure 3.

Dietary sulfur amino acid restriction (SAAR) increases circulating fibroblast growth factor 21 (FGF21) independent of hepatic Atf4. (A, B) Serum concentrations of FGF21 (ng/mL) at 12 h after introduction of experimental diets (left) or at the end of the 10-wk experimental period (right) in male (A) and female (B) mice without or with liver-specific knockdown of Atf4 (Atf4^fl/fl and lsAtf4KO, respectively), fed either a control (Ctrl) diet or subjected to dietary SAAR for the indicated time. (C, D) Hepatic Fgf21 mRNA expression at the end of the 10-wk experimental period in male (C) and female (D) mice, displayed as relative to the Atf4^fl/fl control-fed group in each biological sex. (E) Serum concentrations of FGF21 (ng/mL) at the end of a 12-h experimental period during which male mice were allowed to consume the respective experimental diets. (F) Hepatic Fgf21 mRNA expression, relative to the Atf4^fl/fl control-fed group, at the end of a 12-h experimental period. n = 5–12/group. *P < 0.05 with a main effect of diet. n.s. indicates no statistically significant differences at α = 0.05, as determined by two-factor ANOVA. In case of a significant interaction effect (between diet and genotype), groups not sharing a common letter indicate a statistically significant difference between groups as determined by post hoc analysis using pairwise t tests with Bonferroni correction. Bar chart values are presented as mean ± SEM with individual data points overlaid. Boxplots indicate median values, with upper and lower hinges representing the 25th and 75th percentiles, respectively, and with upper and lower whiskers reaching to the largest and smallest values, respectively, while not extending further than 1.5 times the interquartile range, with individual data points overlaid.