Fig. 5

FXN deficiency impairs insulin sensitivity in adipocytes. (A) Fxn knockdown efficiency in 3T3-L1 cells using Fxn shRNA to generate a stable cell line. Samples were used for subsequent experiments. (B) 3T3-L1 preadipocytes were stained with Nile red for lipid droplets and visualized by confocal microscope. The stable cell lines of Fxn-deficiency (shFxn) and control (NC) were treated with 300 μM of oleic acid (OA) for 48 h, followed by Nile staining. Scale bars, 50 μm. (C) TAG content in 3T3-L1 preadipocytes after OA treatment (300 μM). The same sampling was used as in (B). (D) A schematic diagram of experimental design for shFxn 3T3-L1 differentiation. (E) Relative glucose uptake levels of NC and shFxn 3T3-L1 cells following insulin treatment for 20 min with indicated concentration. (F) The protein levels of p-Akt (s473) and Akt in response to insulin (100 nM) addition in differentiated NC and shFxn 3T3-L1 cells. (G,H) The contents of glycerol and FFAs released into the medium after cells were treated with or without FSK (50 μM) for 4 h. (I–K) The responses of FXN deficient cells to lipolysis agonist FSK (I,J, 20 μM for 48 h) or PGZ (K, 10 μM for 48 h) and insulin addition (100 nM, 20 min). Differentiated NC and shFxn 3T3-L1 cells for (I) and (K); Differentiated primary adipocytes from Y47 and YG8R mice for (J). NC negative control. Values are shown as mean ± SD. n = 3 for each. t-test was used for significance. *P < 0.05, **P < 0.01, ***P < 0.001.