Four Key Steps Control Glycolytic Flux in Mammalian Cells

Abstract

Altered glycolysis is a hallmark of diseases including diabetes and cancer. Despite intensive study of the contributions of individual glycolytic enzymes, systems-level analyses of flux control through glycolysis remain limited. Here, we overexpress in two mammalian cell lines the individual enzymes catalyzing each of the 12 steps linking extracellular glucose to excreted lactate, and find substantial flux control at four steps: glucose import, hexokinase, phosphofructokinase, and lactate export (and not at any steps of lower glycolysis). The four flux-controlling steps are specifically upregulated by the Ras oncogene: optogenetic Ras activation rapidly induces the transcription of isozymes catalyzing these four steps and enhances glycolysis. At least one isozyme catalyzing each of these four steps is consistently elevated in human tumors. Thus, in the studied contexts, flux control in glycolysis is concentrated in four key enzymatic steps. Upregulation of these steps in tumors likely underlies the Warburg effect.

A dynamic model linking cell growth to intracellular metabolism and extracellular by‐product accumulation

“…This implies that mechanisms used to describe, for instance enolase (ENO) or pyruvate carboxylase (PK) kinetics, might need further improvements. Nevertheless, results also indicate that reasonable assumptions were made for the most critical enzymes in glycolytic control, that is, hexokinase (HK), phosphofructokinase (PFK), and lactate dehydrogenase (LDH) (Tanner et al, 2018). PFK has been described to be closely linked to oscillations frequently found in glycolytic rates (Sola‐Penna, Da Silva, Coelho, Marinho‐Carvalho, & Zancan, 2010; Yalcin, Telang, Clem, & Chesney, 2009).…”

Crosstalk between the lncRNA UCA1 and microRNAs in cancer

“…Inhibitor of apoptosisstimulating protein of p53 (iASPP) and the heart 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB2) are the targets of miR-182 and were found to inhibit p53-dependent cell apoptosis and facilitate glioma invasion, respectively [50,51]. In addition, PFKFB2 is also regarded as a critical gene in charge of glycolysis [52], and the UCA1-miR-182-PFKFB2 axis plays an important role in glioma glycolysis [51].…”

Quantitative analysis of how Myc controls T cell proteomes and metabolic pathways during T cell activation

“…This was surprising, given previous observations that Myc deletion reduced Slc2a1 and Slc2a3 mRNA (Wang et al, 2011) and highlights the value of a proteomics approach to quantify the expression patterns of proteins where there may be a disconnect between mRNA and protein expression due to translational regulation (Ricciardi et al, 2018). The expression of both glucose and lactate transporters are key for glycolytic flux (Tanner et al, 2018) and the fact that these are differentially controlled by Myc reveals that upregulation of metabolic pathways during T cell activation is more complex than a simple activation switch or amplifier mediated by a single transcription factor (Nie et al, 2012). The data gives molecular insight into why Myc is so important for T cell glutamine metabolism and glycolysis but they also reveal that T cell metabolic reprogramming requires the coordination of Myc expression with other signalling pathways.…”

“…The study uncovers both Myc dependent and independent restructuring of the T cell proteome during immune activation. Myc was required for the increase in expression of key metabolic pathway proteins; for example, glutamine transporters and glutaminase, key proteins controlling the first steps of glutaminolysis (Newsholme, Crabtree, & Ardawi, 1985); and lactate transporters, a major rate determining step for glycolytic flux (Tanner et al, 2018).…”

“…It was however striking that Myc had a large impact on lactate transporter expression, particularly on the numerically dominant lactate transporter Slc16a1 ( Fig 2D). Lactate transporters control a critical rate limiting step for glycolytic flux (Tanner et al, 2018). Their absence would prevent lactate export leading to intracellular accumulation of lactate which would feedback to suppress glycolytic flux (Doherty et al, 2014).…”