Figure 4.

Stable isotope tracing using [U–¹³C₆] glucose in SFD iRPE cells compared with controls. SFD iRPE cells have increased glucose contribution to the TCA cycle. Steady state isotopic tracing using [U–¹³C₆] glucose was conducted for 24 h, fractional enrichment is displayed on the Y axis. Isotopologues generated through glycolysis and TCA cycle are displayed on the X axis. A, B, When [U–¹³C₆] glucose is broken down via glycolysis, M3 pyruvate (3-carbon labeled Pyruvate) and M3 lactate are generated. C–I, M2 and M4 TCA cycle metabolites are generated during the first and second round of the TCA cycle respectively when pyruvate enters through Acetyl CoA. M2 and M4 glutamate, glutamine and proline are generated when cataplerosis occurs, and TCA intermediates are depleted. Statistics performed were two-tailed unpaired Mann–Whitney test. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001. TCA pathway schematic was generated using BioRender. Graphs were made with GraphPad Prism (n = 13).