Rosiglitazone, a PPARG agonist that binds to the same binding pocket in PPARG as fatty acid, bypasses the need for FABP4 to up-regulate PPARG expression during adipogenesis.

(A) Addition of rosiglitazone (1 μm) to the differentiation stimulus (DMI) rescues the loss of adipogenesis shown in Fig 1F in FABP4-KO OP9 cells and in FABP4-KO OP9 cells transfected with FABP5 siRNA. The percent of differentiated cells was quantitated as in Fig 1D. See also S1D and S1E Fig. (B) The addition of rosiglitazone (1 μm) to the differentiation media (insulin added to the growth media) rescues the loss of adipogenesis in FABP4-KO, FABP5-KO, and DBKO 3T3-F442A cells shown in Fig 1H. See also S2C and S2D and S3 Figs. (C) Citrine-PPARG cells were transfected with FABP4-targeted or control siRNA and were imaged while being induced to differentiate by the standard DMI protocol with and without rosiglitazone added to the DMI stimulus. Knockdown of FABP4 results in loss of differentiation. However, this phenotype was partially rescued by addition of rosiglitazone. (D) OP9 cell lines were stimulated with linoleic acid for 48 hours to induce interaction between FABP4 and PPARG, and then cyclohexamide was added. The cells were fixed at the indicated time points, and immunocytochemistry was performed to measure PPARG protein levels. Three technical replicates for each condition are shown (black dots). The shaded region represents the 95th confidence bounds on the fitted coefficients. Values enclosed in parentheses show lower and upper bounds on the estimated half-life derived from the 95% confidence bounds. The data underlying the graphs in the figure can be found in https://zenodo.org/record/7012787#.Y2I5I0zP3b0. siRNA, small interfering RNA.