Critical role for lactate dehydrogenase A in aerobic glycolysis that sustains pulmonary microvascular endothelial cell proliferation

Abstract

Pulmonary microvascular endothelial cells possess both highly proliferative and angiogenic capacities, yet it is unclear how these cells sustain the metabolic requirements essential for such growth. Rapidly proliferating cells rely on aerobic glycolysis to sustain growth, which is characterized by glucose consumption, glucose fermentation to lactate, and lactic acidosis, all in the presence of sufficient oxygen concentrations. Lactate dehydrogenase A converts pyruvate to lactate necessary to sustain rapid flux through glycolysis. We therefore tested the hypothesis that pulmonary microvascular endothelial cells express lactate dehydrogenase A necessary to utilize aerobic glycolysis and support their growth. Pulmonary microvascular endothelial cell (PMVEC) growth curves were conducted over a 7-day period. PMVECs consumed glucose, converted glucose into lactate, and acidified the media. Restricting extracellular glucose abolished the lactic acidosis and reduced PMVEC growth, as did replacing glucose with galactose. In contrast, slow-growing pulmonary artery endothelial cells (PAECs) minimally consumed glucose and did not develop a lactic acidosis throughout the growth curve. Oxygen consumption was twofold higher in PAECs than in PMVECs, yet total cellular ATP concentrations were twofold higher in PMVECs. Glucose transporter 1, hexokinase-2, and lactate dehydrogenase A were all upregulated in PMVECs compared with their macrovascular counterparts. Inhibiting lactate dehydrogenase A activity and expression prevented lactic acidosis and reduced PMVEC growth. Thus PMVECs utilize aerobic glycolysis to sustain their rapid growth rates, which is dependent on lactate dehydrogenase A.

Pseudomonas aeruginosa Exotoxin Y Is a Promiscuous Cyclase That Increases Endothelial Tau Phosphorylation and Permeability

“…Bacteria were subsequently diluted in PBS to achieve the desired multiplicity of infection (m.o.i.). For bacterial infection, endothelial cells were trypsinized and counted using a Coulter counter (Beckman Coulter) as reported previously (40). Endothelial cells were grown to 12-24 h post-confluence and then infected with P. aeruginosa ExoY or P. aeruginosa ExoY K81M at an m.o.i.…”

Angiogenesis revisited – role and therapeutic potential of targeting endothelial metabolism

“…Although all blood vascular endothelial cell identities (arterial, venous, microvascular) are highly glycolytic in vitro, arterial endothelial cells are comparatively less glycolytic and more oxidative, whereas microvascular-derived endothelial cells are relatively more glycolytic and proliferative. However, the in vivo relevance of these endothelial cell subtype-dependent findings requires further study (De Bock et al, 2013b;Parra-Bonilla et al, 2010). Interestingly, endothelial cells under pathological conditions exhibit characteristics of the Warburg effect -which is commonly associated with hyperproliferative cells -whereby glycolysis increases and oxidative phosphorylation decreases (Delgado et al, 2010;Fijalkowska et al, 2010;Metallo and Vander Heiden, 2013;Mullen and DeBerardinis, 2012).…”

“…Interestingly, endothelial cells under pathological conditions exhibit characteristics of the Warburg effect -which is commonly associated with hyperproliferative cells -whereby glycolysis increases and oxidative phosphorylation decreases (Delgado et al, 2010;Fijalkowska et al, 2010;Metallo and Vander Heiden, 2013;Mullen and DeBerardinis, 2012). Upon activation by factors such as VEGF, endothelial cells increase expression of GLUT-1 as well as that of glycolytic enzymes, such as lactate dehydrogenase-A (LDH-A) and 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3), among others (De Bock et al, 2013b;Parra-Bonilla et al, 2010;Peters et al, 2009;Yeh et al, 2008). By contrast, DLL4-Notch signaling, which suppresses VEGFR2 expression and vascular branching, also decreases glycolytic flux in endothelial cells in vitro by downregulating PFKFB3 (De Bock et al, 2013b) (Fig.…”

Endothelial cell metabolism inhibition: A new approach to the treatment of resistant metastatic colorectal carcinoma

“…De novo lipid synthesis is required to generate bioactive lipids for cell signaling and membrane expansion during the rapid EC growth [12] . increase the expression of their primary glucose transporter (GLUT-1), which is a facilitated diffusion carrier protein, allowing ECs to take up glucose independently from insulin and utilize it as a carbon source for glycolysis and fatty acid synthesis as well [9,13,14] . Hence, targeting the convergence of angiogenic signals on endothelial metabolism would be an effective alternative to anti-VEGF in metastatic CRC therapy.…”