Figure 2
PGC-1α modulates glutamine metabolism in normoxia and hypoxia. (A) Glutamine uptake in NT2196 cells with increased expression of PGC-1α (α-1.1) and control. Cells were cultured in either normoxia or hypoxia for 24 h. Data are represented as fold difference for α-1.1 cells compared to control. Data are presented as means ± S.E.M., n = 5. *P <0.05, paired Student's t-test. (B) Schematic representation depicting metabolomics experiments using [U-13C]-glutamine to evaluate forward (green) and reverse (red) citric acid cycle (CAC) fluxes. Herein, 13C is represented as black circles and endogenous 12C as white circles. (C) Mass isotopomer enrichment of α-ketoglutarate in NT2196 cells with increased expression of PGC-1α (α-1.1) and control (Ctl-1) pulsed with [U-13C]-glutamine in normoxia and hypoxia. Data are presented as means ± S.E.M., n = 6. †P <0.05, paired Student's t-test. (D) Mass isotopomer enrichment of citrate. Data are presented as means ± S.E.M., n = 6. *(m + 4, forward flux) and †(m + 5, reverse flux) P <0.05, paired Student's t-test. (E) Mass isotopomer enrichment of malate. Data are presented as means ± S.E.M., n = 6. *(m + 4, forward flux) and †(m + 3, reverse flux) P <0.05, paired Student's t-test. (F) Mass isotopomer enrichment of fumarate. Data are presented as means ± S.E.M., n = 6. *(m + 4, forward flux) and †(m + 3, reverse flux) P <0.05, paired Student's t-test. For panels C-F, normalized ion amounts were calculated as normalized MDV* multiplied by fold change in steady state levels, relative to Ctl-1 cells in normoxia.