Figure 4.

mTORC1 activation is an upstream event in palmitate induced ATF4 activation. A: AML12 cells were pretreated with or without Torin1 (0.25 µM) or rapamycin (Rapa at 50 nM) for 2 h before palmitate (0.4 mM) exposure for 16 h. Total protein was extracted. Protein abundance of ATF4 and actin were detected by Western blotting. The signal of ATF4 protein band was measured by densitometry and then divided by the signal of its corresponding actin abundance in the same sample. Data are expressed as means ± SD, n = 3 separate experiments. Student’s t test was used for statistical evaluation (***P < 0.001 vs. control). B: AML12 were pretreated with Torin1 (0.25 µM) for 2 h before a 16-h palmitate (0.4 mM) exposure. Total RNA was extracted. ATF4 mRNA levels were detected by real time-qPCR. Data are expressed as means ± SD, n = 4 separated experiments. Differences between the two groups were determined using Student’s t test (***P < 0.001 vs. control). ATF, activating transcription factor.