An in-silico study of the regulation of CHO cells glycolysis

In this work, a kinetic-metabolic model previously developed for CHO cells is used to study glycolysis regulation. The model is assessed for its biological relevance by analyzing its ability to simulate metabolic events induced following a hypoxic perturbation. Feedback and feedforward regulatory mechanisms known to occur to either inhibit or activate fluxes of glycolysis, are implemented in various combined scenarios and their effects on the metabolic response were analyzed. This study aims at characterizing the role of intermediates of glycolysis and of the cell energetic state, described as the AMP-to-ATP ratio, as inhibitors and activators of glycolysis pathway. In addition to the glycolysis pathway, we here describe the transient metabolic response of pathways that are connected to glycolysis, such as the pentose phosphate pathway, TCA cycle, cell bioenergetics system, glutamine and amino acids metabolisms. Taken individually, each regulatory mechanism leads to an oscillatory behavior in response to a hypoxic perturbation, while their combination clearly damps oscillations. However, only the addition of the cell energetic state to the regulatory mechanisms results in a non-oscillating response leading to metabolic flux rate rearrangement corresponding to the anaerobic metabolism expected to prevail under hypoxic conditions. We thus demonstrate in this work, from model simulations, that the robustness of a cell energetic metabolism can be described from a combination of feedback and feedforward inhibition and activation regulatory mechanisms of glycolysis fluxes, involving intermediates of glycolysis and the cell energetic state itself.