(176f) Probing Mammalian Cell Metabolism Using Stable Isotope Tracers and Metabolic Flux Analysis

Metabolism is central to virtually all cellular functions, and cells must negotiate their surrounding microenvironment to effectively utilize their surrounding nutrients.  A detailed understanding of how metabolic pathways are regulated is necessary to design better culture systems and identify therapeutic targets in diseases where metabolism is deregulated.  To this end we apply stable isotope tracers, mass spectrometry, and metabolic flux analysis to characterize central carbon metabolism in mammalian cells, including normal cells and tumor cell lines.  We have developed unique, tracer-based methods to probe glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle.  Using these approaches we have identified the importance of reductive glutamine metabolism for cells proliferating under low oxygen tensions, whereby glutamine rather than glucose serves as the primary carbon source for lipid synthesis.  We have extended these findings to further elucidate how cells obtain amino acids for cell growth and regenerate cofactors for reductive biosynthesis.  These findings highlight a critical role of oxygen and reductive TCA metabolism in supporting cell growth under hypoxia.