Lactate and glucose concomitant consumption as a self-regulated pH detoxification mechanism in HEK293 cell cultures.
One of the most important limitations of mammalian cell-based processes is the secretion and accumulation of lactate as a by-product of their metabolism. Among the cell lines commonly used in industrial bioprocesses, HEK293 has been gaining importance over the last years. Up recently, HEK293 cells were known to consume lactate in late stages of cell culture usually when glucose and/or glutamine were depleted from media. Remarkably, in both scenarios, no significant cell growth was reported. However, we have observed a different metabolic behavior regarding lactate production and consumption in HEK293 cultures. HEK293 cells were able to co-metabolize glucose and lactate simultaneously, even in exponentially growing cell cultures. Our deep study of the effects of environmental conditions on lactate metabolism revealed that pH was the key to trigger the metabolic shift from lactate production to lactate and glucose concomitant consumption. Remarkably, this shift could be triggered at will when pH was set at 6.8. Even more interesting was the fact that lowering pH to 6.6 and supplementing media with exogenous lactate resulted in co-consumption of glucose and lactate from the beginning of cell culture, without affecting cell growth or protein productivity. On the contrary, cell growth was clearly hampered at this low pH if extracellular lactate was lacking. From our results, we hypothesize that HEK293 cells metabolize extracellular lactate as a strategy for pH detoxification, by means of co-transporting extracellular protons together with lactate into the cytosol. This novel hypothesis for unraveling lactate metabolism in HEK293 cells could open a door to re-direct genetic engineering strategies in order to obtain more efficient cell lines and also to further develop animal cell technology applications.
Chemical Engineering Department, Universitat Autònoma de Barcelona, Edifici Q, Campus Bellatera. Carretera de Cerdanyola, s/n. 08193 Bellatera, Barcelona, Spain. Leticia.Liste@uab.cat.
Leticia
L
Liste-Calleja
Chemical Engineering Department, Universitat Autònoma de Barcelona, Edifici Q, Campus Bellatera. Carretera de Cerdanyola, s/n. 08193 Bellatera, Barcelona, Spain.
Martí
M
Lecina
Chemical Engineering Department, Universitat Autònoma de Barcelona, Edifici Q, Campus Bellatera. Carretera de Cerdanyola, s/n. 08193 Bellatera, Barcelona, Spain.
Jonatan
J
Lopez-Repullo
Chemical Engineering Department, Universitat Autònoma de Barcelona, Edifici Q, Campus Bellatera. Carretera de Cerdanyola, s/n. 08193 Bellatera, Barcelona, Spain.
Joan
J
Albiol
Chemical Engineering Department, Universitat Autònoma de Barcelona, Edifici Q, Campus Bellatera. Carretera de Cerdanyola, s/n. 08193 Bellatera, Barcelona, Spain.
Carles
C
Solà
Chemical Engineering Department, Universitat Autònoma de Barcelona, Edifici Q, Campus Bellatera. Carretera de Cerdanyola, s/n. 08193 Bellatera, Barcelona, Spain.
Jordi Joan
JJ
Cairó
D001692:Biological Transport; D003470:Culture Media / Q000737:chemistry; D004847:Epithelial Cells / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008658:Inactivation, Metabolic; D019344:Lactic Acid / Q000378:metabolism*
D003470:Culture Media; D019344:Lactic Acid; D005947:Glucose
Co-metabolism; HEK293; Lactate; Metabolic shift; Warburg effect; pH