Fig. 5: Cytosolic serine levels controlled by SHMT1 modulate ROS formation and ATP/energy profile.
Effect of nutrients on ATP and ROS levels in A549 cells. The effect of 400 μM Ser ± 4LFPG or Gly ± SARC supplementations, on ATP levels (A) and ROS production (B) in A549 cells grown in MEM as compared to cells grown in complete medium RPMI or 50% brain extracellular fluid (BEF). Effect of the inhibition of Ser/Gly uptake on ATP (C) and ROS levels (D) in A549 cells grown in RPMI complete (10% FBS) or 50% BEF in MEM. The levels of the indicated parameters were assayed after incubation of the cells with 100 μM of 4LFPG and/or SARC. ATP concentration measured for RPMI (A) and Ct (C) are 29.4 ± 3.4 nmol/mg protein and 19.6 ± 1.9 nmol/mg protein, respectively. For all the experiments in (A–D) n = 4. OCR (E) and ECAR (F) analysis (n = 4) of A549 cells in RPMI (black) or RPMI with increased serine concentration (385 μM, blue in the figure) and in combination with 4LFPG (red); a representative experiment is shown (data are the mean of at least five wells ± SD). Asterisks refer to P values for serine vs. 4LFPG. P values for RPMI vs. serine samples are <0.01 for both OCR and ECAR (not shown). G Migration of A549 cells to 50% serum after treatment with 25 μM SARC alone or in the presence of 50 μM NADPH or GSH or with 25 μM ATP or hypoxanthine12,46. The graphs represent three independent experimental replicates. *P < 0.05; **P < 0.01; ***P < 0.005.
